[clang] [Clang] Don't build static analyzer if disabled (PR #212024)

[Alexis Engelke via cfe-commits]

aengelke wrote:

Yes, that sounds right. A BUILD_SHARED_LIBS mode (LLVM has this, I don't think Clang has this currently) results in substantially slower startup times and binaries and slows down tests -- at least for LLVM it slows down tests by ~60%.

https://github.com/llvm/llvm-project/pull/212024