Clean up some comments I missed when switching from NestedMacroInstantiations -> NestedMacroExpansions.
Clean up some comments I missed when switching from
NestedMacroInstantiations -> NestedMacroExpansions.

With this change, libclang should be completely converted except for
uses of SourceManger and SourceLocation APIs, and the C bindings for
those APIs.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@135149 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang