x86_64 ABI: "is passed in regs" computation for va_arg was broken for things passed in mixed registers.
x86_64 ABI: "is passed in regs" computation for va_arg was broken for
things passed in mixed registers.

This knocks out 8 x86_64 failures.


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@64958 91177308-0d34-0410-b5e6-96231b3b80d8

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