[X86] Change avx512-gather-scatter-intrin.ll to use x86_64-unknown-unknown instead of x86_64-apple-darwin. NFC
[X86] Change avx512-gather-scatter-intrin.ll to use x86_64-unknown-unknown instead of x86_64-apple-darwin. NFC

Will help with an upcoming patch.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@351521 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm