[mlir] Assertion `&typeSample.getDialect() != typeSample.getContext()->getLoadedDialect<BuiltinDialect>() && "unexpected data layout entry for built-in type"' failed

The following code:

```mlir
module attributes {dlti.dl_spec = #dlti.dl_spec} {
module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry>} {
}
}
```

Resulted in this output:
```
mlir-opt: /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Dialect/DLTI/DLTI.cpp:338: LogicalResult combineOneSpec(DataLayoutSpecInterface, llvm::MapVector &, llvm::MapVector &): Assertion `&typeSample.getDialect() != typeSample.getContext()->getLoadedDialect() && "unexpected data layout entry for built-in type"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0. Program arguments: ./llvm-mlir-build/bin/mlir-opt /tmp/test.mlir
#0 0x0000556f3d829b46 ___interceptor_backtrace (./llvm-mlir-build/bin/mlir-opt+0x734eb46)
#1 0x0000556f3d912ba7 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/llvm/lib/Support/Unix/Signals.inc:931:13
#2 0x0000556f3d9159fa llvm::sys::RunSignalHandlers() /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/llvm/lib/Support/Signals.cpp:0:5
#3 0x0000556f3d9159fa SignalHandler(int, siginfo_t*, void*) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/llvm/lib/Support/Unix/Signals.inc:457:3
#4 0x00007fc5e6270520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#5 0x00007fc5e62c49bc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969bc)
#6 0x00007fc5e6270476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#7 0x00007fc5e62567f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#8 0x00007fc5e625671b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#9 0x00007fc5e6267e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#10 0x0000556f4e31b655 combineOneSpec(mlir::DataLayoutSpecInterface, llvm::MapVector, llvm::DenseMap, llvm::detail::DenseMapPair>, llvm::SmallVector>, 0u>, 0u>&, llvm::MapVector, llvm::detail::DenseMapPair>, llvm::SmallVector, 0u>, 0u>&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Dialect/DLTI/DLTI.cpp:336:5
#11 0x0000556f4e31a34d mlir::DataLayoutSpecAttr::combineWith(llvm::ArrayRef) const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Dialect/DLTI/DLTI.cpp:368:7
#12 0x0000556f4e32fb2c mlir::detail::DataLayoutSpecInterfaceInterfaceTraits::Model::combineWith(mlir::detail::DataLayoutSpecInterfaceInterfaceTraits::Concept const*, mlir::Attribute, llvm::ArrayRef) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-mlir-build/tools/mlir/include/mlir/Interfaces/DataLayoutAttrInterface.h.inc:712:60
#13 0x0000556f50f45d89 mlir::DataLayoutSpecInterface::combineWith(llvm::ArrayRef) const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-mlir-build/tools/mlir/include/mlir/Interfaces/DataLayoutAttrInterface.cpp.inc:32:14
#14 0x0000556f50f45d89 getCombinedDataLayout(mlir::Operation*) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Interfaces/DataLayoutInterfaces.cpp:434:20
#15 0x0000556f50f451ab mlir::Attribute::operator!() const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/include/mlir/IR/Attributes.h:48:40
#16 0x0000556f50f451ab mlir::detail::verifyDataLayoutOp(mlir::Operation*) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Interfaces/DataLayoutInterfaces.cpp:449:7
#17 0x0000556f4e31f5b4 mlir::DLTIDialect::verifyOperationAttribute(mlir::Operation*, mlir::NamedAttribute) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/Dialect/DLTI/DLTI.cpp:658:14
#18 0x0000556f513be0d2 llvm::LogicalResult::failed() const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/llvm/include/llvm/Support/LogicalResult.h:43:43
#19 0x0000556f513be0d2 llvm::failed(llvm::LogicalResult) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/llvm/include/llvm/Support/LogicalResult.h:71:58
#20 0x0000556f513be0d2 (anonymous namespace)::OperationVerifier::verifyOnEntrance(mlir::Operation&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:307:11
#21 0x0000556f513be0d2 _ZZN12_GLOBAL__N_117OperationVerifier15verifyOperationERN4mlir9OperationEENK3$_2clIS2_EEDaPT_ /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:439:45
#22 0x0000556f513be0d2 _ZZN12_GLOBAL__N_117OperationVerifier15verifyOperationERN4mlir9OperationEENK3$_1clIZNS0_15verifyOperationES3_E3$_2EEDaOT_N4llvm12PointerUnionIJPS2_PNS1_5BlockEEEE /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:419:16
#23 0x0000556f513be0d2 (anonymous namespace)::OperationVerifier::verifyOperation(mlir::Operation&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:438:16
#24 0x0000556f513be0d2 (anonymous namespace)::OperationVerifier::verifyOpAndDominance(mlir::Operation&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:91:14
#25 0x0000556f513be936 (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0::operator()(mlir::Operation*) const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/lib/IR/Verifier.cpp:368:9
#26 0x0000556f513be936 auto void mlir::parallelForEach(mlir::MLIRContext*, mlir::Operation**, mlir::Operation**, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0&&)::'lambda'(mlir::Operation**&&)::operator()(mlir::Operation**&&) const /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/include/mlir/IR/Threading.h:120:12
#27 0x0000556f513be936 llvm::LogicalResult mlir::failableParallelForEach(mlir::MLIRContext*, mlir::Operation**, mlir::Operation**, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0&&)::'lambda'(mlir::Operation**&&)>(mlir::MLIRContext*, mlir::Operation**, mlir::Operation**, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0&&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/include/mlir/IR/Threading.h:46:18
#28 0x0000556f513be936 void mlir::parallelForEach(mlir::MLIRContext*, mlir::Operation**, mlir::Operation**, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0&&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/include/mlir/IR/Threading.h:119:9
#29 0x0000556f513be936 void mlir::parallelForEach&, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0>(mlir::MLIRContext*, llvm::SmallVector&, (anonymous namespace)::OperationVerifier::verifyOnExit(mlir::Operation&)::$_0&&) /home/fuzz/WorkSpace/fusion-fuzz/projects/mlir/llvm-project/mlir/include/mlir/IR/Threading.h:131:3
```

An inner module whose `dlti.dl_spec` re-states an entry of the outer spec — here
`index = 32` written once in the sugared form and once as an explicit
`#dlti.dl_entry` — makes `combineOneSpec` assert while merging the two specs.
Both specs are individually well-formed and the IR verifies.

A closely related crash with the same shape, in the LLVM dialect's pointer-spec
reader rather than in `combineOneSpec`:

```mlir
module attributes {dlti.dl_spec = #dlti.dl_spec : vector<4xi64>>} {
module attributes {dlti.dl_spec = #dlti.dl_spec : vector<4xi64>>} {
}
}
```

```
mlir-opt: llvm/include/llvm/Support/Casting.h:566: ... [To = mlir::DenseIntElementsAttr, From = mlir::Attribute]: Assertion `isa(Val) && "cast() argument of incompatible type!"' failed.
#11 mlir::LLVM::extractPointerSpecValue(mlir::Attribute, mlir::LLVM::PtrDLEntryPos)
```

To reproduce:
```
mlir-opt --canonicalize ./min.mlir
```

Commit:
```
8c536a50e6f06e06031500e8933a34226cca1ec4
```

Operating System:
```
Ubuntu 22.04, Docker image fusion-fuzz-mlir:latest
```

Start with combineOneSpec in mlir/lib/Dialect/DLTI/DLTI.cpp and the getCombinedDataLayout path in mlir/lib/Interfaces/DataLayoutInterfaces.cpp, reproducing with mlir-opt --canonicalize ./min.mlir. Also inspect LLVM::extractPointerSpecValue for the related pointer-spec crash. Done means both nested data-layout examples are handled without assertions and the input no longer crashes verification or canonicalization.

Written by the indexing model from the issue text.