[clang] [clang][ssaf] Preserve AST after codegen for SSAF extractors (PR #191058)

[Balázs Benics via cfe-commits]

steakhal wrote:

I'm currently investigating a build bot failure on `fuchsia-x86_64-linux` caused by this patch:
https://lab.llvm.org/buildbot/#/builders/11/builds/37623
```
FAIL: Clang :: Analysis/Scalable/extraction-works-alongside-compilation.cpp (675 of 24499)
******************** TEST 'Clang :: Analysis/Scalable/extraction-works-alongside-compilation.cpp' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 7
rm -rf /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.o /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.json
# executed command: rm -rf /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.o /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.json
# RUN: at line 8
/var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/bin/clang -c /var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/clang/test/Analysis/Scalable/extraction-works-alongside-compilation.cpp -o /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.o -mllvm -debug-only=codegenaction 2>&1 | grep "Clearing AST"
# executed command: /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/bin/clang -c /var/lib/buildbot/fuchsia-x86_64-linux/llvm-project/clang/test/Analysis/Scalable/extraction-works-alongside-compilation.cpp -o /var/lib/buildbot/fuchsia-x86_64-linux/build/llvm-build-9c_m3hqg/tools/clang/test/Analysis/Scalable/Output/extraction-works-alongside-compilation.cpp.tmp.o -mllvm -debug-only=codegenaction
# note: command had no output on stdout or stderr
# error: command failed with exit status: 1
# executed command: grep 'Clearing AST'
# note: command had no output on stdout or stderr
# error: command failed with exit status: 1
```

https://github.com/llvm/llvm-project/pull/191058