Fix unused-function warning differently from r220853
Fix unused-function warning differently from r220853

Rather than executing this code only needed for an assertion even in a
non-asserts build, just roll the function into the assert. The assertion
text literally describes the two cases so it doesn't seem like this
benefits much from having a separate function (& have to hassle about
ifndef NDEBUG it out, etc)

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@220970 91177308-0d34-0410-b5e6-96231b3b80d8

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