[X86] Use MSVC's __cpuidex intrinsic instead of inline assembly in getHostCPUName...

[X86] Use MSVC's __cpuidex intrinsic instead of inline assembly in getHostCPUName/getHostCPUFeatures for 32-bit builds too.

We're already using it in 64-bit builds because 64-bit MSVC doesn't support inline assembly.

As far as I know we were using inline assembly because at the time the code was added we had to support MSVC 2008 pre-SP1 while the intrinsic was added to MSVC in SP1. Now that we don't have to support that we should be able to just use the intrinsic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308163 91177308-0d34-0410-b5e6-96231b3b80d8