[clang] [clang-repl] Lay the foundation of pretty printing for C. (PR #89811)

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

Not sure, nothing in cmake cmd:

```
cmake -DLLVM_APPEND_VC_REV=OFF -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_CCACHE_BUILD=ON -DLLVM_USE_LINKER=lld -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF -DCMAKE_C_COMPILER=/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/llvm_build0/bin/clang -DCMAKE_CXX_COMPILER=/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/llvm_build0/bin/clang++ -DLLVM_ENABLE_PLUGINS=OFF '-DLLVM_ENABLE_PROJECTS='\''clang;lld;mlir'\''' -DLLVM_USE_SANITIZER=HWAddress -DLLVM_ENABLE_LIBCXX=ON '-DCMAKE_C_FLAGS=-nostdinc++ -isystem /b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/include -isystem /b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/include/c++/v1 -fsanitize=hwaddress -mllvm -hwasan-use-after-scope=1 -Wl,--rpath=/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib -L/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib -w' '-DCMAKE_CXX_FLAGS=-nostdinc++ -isystem /b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/include -isystem /b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/include/c++/v1 -fsanitize=hwaddress -mllvm -hwasan-use-after-scope=1 -Wl,--rpath=/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib -L/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib -w' '-DCMAKE_EXE_LINKER_FLAGS=-Wl,--rpath=/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib -L/b/sanitizer-aarch64-linux-bootstrap-hwasan/build/libcxx_build_hwasan/lib' /b/sanitizer-aarch64-linux-bootstrap-hwasan/build/llvm-project/llvm
```

https://github.com/llvm/llvm-project/pull/89811