Use -fobjc-runtime=macosx10.7 instead of obsolete -fobjc-runtime-has-weak.
Use -fobjc-runtime=macosx10.7 instead of obsolete -fobjc-runtime-has-weak.

This should unbreak the buildbots (r162220).

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@162232 91177308-0d34-0410-b5e6-96231b3b80d8

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