[llvm] [InlineAsm] wrap ConstraintCode in enum class NFC (PR #66003)

[Reid Kleckner via llvm-commits]

rnk wrote:

My approach to managing cmake config options is to put them in a shell script (`reconfig.sh`) in the build directory, and to `rm -rf CMakeCache.txt CMakeFiles` when I encounter problems with that. In other words, I don't trust CMakeCache to hold my configuration for me, I write it down. CMake leaves a lot to be desired. =/

https://github.com/llvm/llvm-project/pull/66003