Add the built-in candidate set reduction hueristic to '+=', '-=', '*=' and '/=' builtin operators and fixes a logic bug exposed by doing this.
Add the built-in candidate set reduction hueristic
to '+=', '-=', '*=' and '/=' builtin operators and
fixes a logic bug exposed by doing this.



git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@84538 91177308-0d34-0410-b5e6-96231b3b80d8

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