[gn build] Port 95a9299

Author: llvmgnsyncbot

llvm/utils/gn/secondary/clang-tools-extra/clang-tidy/objc/BUILD.gn

@@ -16,6 +16,7 @@ static_library("objc") {
     "DeallocInCategoryCheck.cpp",
     "ForbiddenSubclassingCheck.cpp",
     "MissingHashCheck.cpp",
+    "NSDateFormatterCheck.cpp",
     "NSInvocationArgumentLifetimeCheck.cpp",
     "ObjCTidyModule.cpp",
     "PropertyDeclarationCheck.cpp",