Removed unused variable [NFC]
Removed unused variable [NFC]

The compiler warned:
../tools/clang/lib/StaticAnalyzer/Core/RetainSummaryManager.cpp:329:19: error: unused variable 'MD' [-Werror,-Wunused-variable]
  if (const auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
                  ^
1 error generated.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@340524 91177308-0d34-0410-b5e6-96231b3b80d8

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