Make the __builtin_c[lt]zs builtins target independent.

There is really no reason to have these only available on x86. It's
just __builtin_c[tl]z for shorts.

Modernize the test while at it.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149183 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed