Per PR2773, define __USER_LABEL_PREFIX__ for x86-32 Linux and Windows.
Per PR2773, define __USER_LABEL_PREFIX__ for x86-32 Linux and Windows.

If you're on some other platform, the correct definition for this macro 
would be appreciated; to find the correct definition, just run the 
following command:

echo | gcc -dM -E - | grep USER_LABEL_PREFIX



git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@55869 91177308-0d34-0410-b5e6-96231b3b80d8

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