[Caching] Do not embed extra ClangTarget in swiftmodule

When direct cc1 mode is used, the cc1 arguments are generated from extra
clang targets so there is no need to add this extra argument.
Furthermore, the `--target=` is a clang driver argument and is not valid
under cc1 mode.

Needed for: rdar://134090397

Author: cachemeifyoucan

lib/Frontend/Frontend.cpp

@@ -233,7 +233,8 @@ SerializationOptions CompilerInvocation::computeSerializationOptions(
   } else {
     serializationOpts.ExtraClangOptions = getClangImporterOptions().ExtraArgs;
   }
-  if (LangOpts.ClangTarget) {
+  if (LangOpts.ClangTarget &&
+      !getClangImporterOptions().DirectClangCC1ModuleBuild) {
     serializationOpts.ExtraClangOptions.push_back("--target=" +
                                                   LangOpts.ClangTarget->str());
   }

test/CAS/embedded-Xcc.swift

@@ -0,0 +1,29 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -scan-dependencies -module-name Test -module-cache-path %t/clang-module-cache -O -g \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib \
+// RUN:   %t/main.swift -o %t/deps.json -swift-version 5 -cache-compile-job -cas-path %t/cas -Xcc -DTEST=1
+
+// RUN: %{python} %S/Inputs/GenerateExplicitModuleMap.py %t/deps.json > %t/map.json
+// RUN: llvm-cas --cas %t/cas --make-blob --data %t/map.json > %t/map.casid
+
+// RUN: %{python} %S/Inputs/BuildCommandExtractor.py %t/deps.json Test > %t/MyApp.cmd
+
+// RUN: echo %t/main.swift > %t/inputs.FileList
+// RUN: %target-swift-frontend -emit-module -o %t/Test.swiftmodule -g -O \
+// RUN:   -cache-compile-job -cas-path %t/cas -swift-version 5 \
+// RUN:   -disable-implicit-swift-modules -swift-version 5 -enable-cross-import-overlays \
+// RUN:   -disable-implicit-string-processing-module-import -disable-implicit-concurrency-module-import -parse-stdlib \
+// RUN:   -module-name Test -explicit-swift-module-map-file @%t/map.casid \
+// RUN:   -filelist %t/inputs.FileList @%t/MyApp.cmd
+
+// RUN: llvm-bcanalyzer --dump %t/Test.swiftmodule | %FileCheck %s
+
+// CHECK: <XCC abbrevid=6/> blob data = '-cc1'
+// CHECK: <XCC abbrevid=6/> blob data = '-D'
+// CHECK: <XCC abbrevid=6/> blob data = 'TEST=1'
+// CHECK-NOT: <XCC abbrevid=6/> blob data = '--target=
+
+//--- main.swift
+public func test() {}