Missed optimization: ( (%0 + 1) - %1 == 1 ) ==> ( %0 == %1 )

The following reduced IR is derived from https://github.com/wireshark/wireshark/blob/b3a991b9bb9f01806ed195ee44b191798bfa298e/epan/dissectors/packet-giop.c#L3198

Godbolt: https://godbolt.org/z/T1h7xeb4e
alive2 proof: https://alive2.llvm.org/ce/z/-vL_wF

```llvm
define i1 @get_CDR_fixed(i32 %0, i32 %1, ptr %2) {
.peel.begin:
%3 = add i32 %0, 1
%4 = sub i32 %3, %1
%exitcond.peel.not = icmp eq i32 %4, 1
ret i1 %exitcond.peel.not
}
```

expected:
```llvm
define i1 @tgt(i32 %0, i32 %1, ptr %2) {
.peel.begin:
%exitcond.peel.not = icmp eq i32 %0, %1
ret i1 %exitcond.peel.not
}
```