[PM/AA] Cleanup comments, formatting, and organization of the AA interface prior to making more substantial and invasive changes.
[PM/AA] Cleanup comments, formatting, and organization of the AA
interface prior to making more substantial and invasive changes.

No functionality changed, and should hopefully keep subsequent patches
as clean and focused as possible in addition to making the comments and
such more clear.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@242964 91177308-0d34-0410-b5e6-96231b3b80d8

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