clang/test/Rewriter/rewrite-modern-extern-c-func-decl.mm: Remove XFAIL and add -U__declspec. mingw32 tends to define built-in __declspec.
clang/test/Rewriter/rewrite-modern-extern-c-func-decl.mm: Remove XFAIL and add -U__declspec. mingw32 tends to define built-in __declspec.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@155910 91177308-0d34-0410-b5e6-96231b3b80d8

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