[RegionPass] Fix forgotten "!".
[RegionPass] Fix forgotten "!".

Commit r355068 "Fix IR/Analysis layering issue with OptBisect" uses the
template

   return Gate.isEnabled() && !Gate.shouldRunPass(this, getDescription(...));

for all pass kinds. For the RegionPass, it left out the not operator,
causing region passes to be skipped as soon as a pass gate is used.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@355733 91177308-0d34-0410-b5e6-96231b3b80d8

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