Using an explicit cast to work around MSVC 2013 not picking the conversion operator as expected. NFC, should fix the MSVC build bots.
Using an explicit cast to work around MSVC 2013 not picking the conversion operator as expected. NFC, should fix the MSVC build bots.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@219116 91177308-0d34-0410-b5e6-96231b3b80d8

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,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