Change TargetParser enum names to avoid macro conflicts (clang)

sys/time.h on Solaris (and possibly other systems) defines "SEC" as "1"
using a cpp macro.  The result is that this fails to compile.

Fixes https://llvm.org/PR23482

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@237113 91177308-0d34-0410-b5e6-96231b3b80d8