Do codegen correctly for va_start/end/copy on architectures where  va_list is a struct, like x86-64.
Do codegen correctly for va_start/end/copy on architectures where 
va_list is a struct, like x86-64.

If anyone has a better idea for how to do the check in the if 
statements, suggestions are welcome.



git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@62582 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-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,apple/swift-clang,apple/swift-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