The LLVM_VERSION_SUFFIX is not reflected in Clang's version

[zmodem]

For example, the current trunk version is 15.0.0git:

$ ./opt --version
LLVM (http://llvm.org/):
  LLVM version 15.0.0git
  Optimized build with assertions.
  Default target: x86_64-unknown-linux-gnu
  Host CPU: broadwell

however, this isn't reflected in Clang's --version output:

$ ./clang --version
clang version 15.0.0 (https://github.com/llvm/llvm-project 52dbee98212c7594852730f671303ecf7d51b7ba)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /work/llvm.monorepo/build.release/bin/.

This is confusing, as it looks to users like the Clang version is the final 15.0.0 release, while it's really not.