[ExplicitModule] Include -Xcc -D into module hash

The decision to exclude `-Xcc -D` options from swift module hash
actually doesn't help to solve the problem. It wouldn't reduce the
module variants (or the number of swiftmodule build commands) because
the command-line also encodes all the clang PCM dependencies that do get
affected by `-Xcc` flags.

To avoid the false sharing and the nondeterministic build products,
include most of the `-Xcc` flags, except include search path, into swift
module hash.

rdar://132046247

lib/Serialization/ScanningLoaders.cpp

@@ -186,8 +186,7 @@ SwiftModuleScanner::scanInterfaceFile(Twine moduleInterfacePath,
           Args.push_back("-direct-clang-cc1-module-build");
           auto *importer =
               static_cast<ClangImporter *>(Ctx.getClangModuleLoader());
-          for (auto &Arg : importer->getSwiftExplicitModuleDirectCC1Args(
-                   /*isInterface=*/true)) {
+          for (auto &Arg : importer->getSwiftExplicitModuleDirectCC1Args()) {
             Args.push_back("-Xcc");
             Args.push_back(Arg);
           }