[InlineCost] Fix a couple comments. NFC
[InlineCost] Fix a couple comments. NFC

Replace "unary operator" with "unary instruction" in visitUnaryInstruction since
we now have a UnaryOperator class which might needs its own visit function.

Fix a copy/paste in visitCastInst that appears to have been copied from
visitPtrToInt.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@361794 91177308-0d34-0410-b5e6-96231b3b80d8

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