[X86] Really make the pointer arguments to avx512 gather/scatter intrinsics...

[X86] Really make the pointer arguments to avx512 gather/scatter intrinsics 'void*' to match gcc and Intel's documentation.

The avx2 gather intrinsics are documented to use 'int', 'long long', 'float', or 'double' *. So I'm leaving those. This matches gcc.

I tried to do this in r350696, but I only updated the header not the builtin definition.

llvm-svn: 350785