[AliasAnalysis] Shrink AliasResults; NFC
[AliasAnalysis] Shrink AliasResults; NFC

We're persisting AliasResults in some places in MemorySSA, so the size
of these now matters a little bit (well, 8 regular-sized bits, to be
precise).

Do the same for ModRefInfo for consistency.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@327201 91177308-0d34-0410-b5e6-96231b3b80d8

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