[analyzer] [NFC] Introduce separate targets for testing the analyzer:...

[analyzer] [NFC] Introduce separate targets for testing the analyzer: check-clang-analyzer and check-clang-analyzer-z3

Current testing setup for analyzer tests with Z3 is rather inconvenient:

There's no way to run the analyzer tests separately (I use
LIT_FILTER=Analysis ninja check-clang, but a direct target is nicer).

When Clang is built with Z3 support, there's no way to *not* run tests
with Z3 solver, and this is often desired, as tests with Z3 solver take
a very long time.

This patch introduces two extra targets:

 - check-clang-analyzer
 - check-clang-analyzer-z3

which solve those problems.

Differential Revision: https://reviews.llvm.org/D50594

llvm-svn: 339629