profile_creator.cc:138] Error reading profile.

when I record a profile via:
```sh
➜ llvm-project git:(master) ✗ perf record -g -F3200 ./foo
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.002 MB perf.data (12 samples) ]
➜ llvm-project git:(master) ✗ /android1/autofdo/create_llvm_prof --binary=foo --profile=perf.data --out=perf.proto
E0623 16:13:15.980063 116888 perf_parser.cc:270] Mapped 25% of samples, expected at least 95%
```
(no problem) but
```sh
➜ llvm-project git:(master) ✗ perf record --call-graph dwarf -F32000 ./foo
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.567 MB perf.data (70 samples) ]
➜ llvm-project git:(master) ✗ /android1/autofdo/create_llvm_prof --binary=foo --profile=perf.data --out=perf.proto
E0623 16:12:40.868065 116624 sample_info_reader.cc:272] PERF_SAMPLE_REGS_USER is not yet supported.
E0623 16:12:40.868284 116624 sample_info_reader.cc:513] Read/skipped 56 bytes, expected 8440 bytes.
E0623 16:12:40.868356 116624 profile_creator.cc:138] Error reading profile.
```
It seems that `--call-graph dwarf` doesn't work, but `-g` does? (DWARF debug info vs frame pointers for unwinding?)