Check for required target features when evaluating LLVM intrinsics

[eduardosm]

Many LLVM intrinsics require some target features (e.g., llvm.x86.sse.* intrinsics generally require the x86 SSE feature)-

We are not currently checking whether they are enabled or not, since intrinsics are not defined with a #[target_feature(enable = "...")] attribute.

Noticed in #3176 (comment).