[NVPTX, CUDA] Improved feature constraints on NVPTX target builtins.

When NVPTX TARGET_BUILTIN specifies sm_XX or ptxYY as required feature,
consider those features available if we're compiling for GPU >= sm_XX or have
enabled PTX version >= ptxYY.

Differential Revision: https://reviews.llvm.org/D45061

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@329829 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed