[unittest] Skip W+X MappedMemoryTests when MPROTECT is enabled
[unittest] Skip W+X MappedMemoryTests when MPROTECT is enabled

Skip all MappedMemoryTest variants that rely on memory pages being
mapped for MF_WRITE|MF_EXEC when MPROTECT is enabled on NetBSD.  W^X
protection causes all those mmap() calls to fail, causing the tests
to fail.

Differential Revision: https://reviews.llvm.org/D54080

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@347337 91177308-0d34-0410-b5e6-96231b3b80d8

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