Enable _rotl, _lrotl, _rotr, _lrotr on all platforms.

The above builtins are currently implemented for MSVC mode, however GCC
also implements these.  This patch enables them for all platforms.

Additionally, this corrects the type for these builtins to always be
'long int' to match the specification in the Intel Intrinsics Guide.

Change-Id: Ida34be98078709584ef5136c8761783435ec02b1
llvm-svn: 355322