[flang-commits] [flang] [flang][fir] Add fir.if -> scf.if and add filecheck test file (PR #142965)

[Lei Huang via flang-commits]

lei137 wrote:

Sorry.  I need to revert this patch since the builder [flang-ppc64](https://lab.llvm.org/buildbot/#/builders/201) have been red for 4 days due to the new tc segfaults on it:
```
$ fir-opt  --fir-to-scf /home/lei/llvm/community/llvm-project/flang/test/Fir/FirToSCF/if.fir --fir-to-scf
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: fir-opt --fir-to-scf /home/lei/llvm/community/llvm-project/flang/test/Fir/FirToSCF/if.fir --fir-to-scf
Segmentation fault (core dumped)
```

https://github.com/llvm/llvm-project/pull/142965