Clean up variable template handling a bit, and correct the behavior of name
lookup when declaring a variable template specialization.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199438 91177308-0d34-0410-b5e6-96231b3b80d8
Add implementations of _cpuid and _xgetbv to Intrin.h

The _cpuid() implementation is the same as in lib/Headers/cpuid.h
with the parameter names adjusted to match the interface.

_xgetbv just does what the Intel manual says.

Differential Revision: http://llvm-reviews.chandlerc.com/D2564

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199439 91177308-0d34-0410-b5e6-96231b3b80d8