Remove unused variables '__kmp_build_check_*'

As an ongoing effort to sanitize the openmp code, this one word change
eliminates creating 1 byte arrays named __kmp_build_check_* and instead
creates one byte array types.  The KMP_BUILD_ASSERT macro still offers the same
functionality; array types with negative number of elements is illegal 
and will cause a compiler failure.

llvm-svn: 239337