Add default -Wall -Werror or -Wall.

* When -Wno-error and -Werror are not used:
  add -Wall to the front of cflags
  if the project is in the WarningAllowedProjects,
  otherwise add -Wall -Werror.
* Add -Wall -Werror to ndk_library build targets.
* Collect names of modules with -Wno-error or without -Werror,
  and pass them to makefile variables:
      SOONG_MODULES_USING_WNO_ERROR
      SOONG_MODULES_ADDED_WERROR
      SOONG_MODULES_ADDED_WALL
* Generate ANDROID_WARNING_ALLOWED_PROJECTS for old makefiles.

Bug: 66996870
Test: normal build
Change-Id: I31385e12b80ca946c7395a5a184ef259b029aac6

cc/ndk_library.go

@@ -251,6 +251,8 @@ func addStubLibraryCompilerFlags(flags Flags) Flags {
 		"-Wno-incompatible-library-redeclaration",
 		"-Wno-builtin-requires-header",
 		"-Wno-invalid-noreturn",
+		"-Wall",
+		"-Werror",
 		// These libraries aren't actually used. Don't worry about unwinding
 		// (avoids the need to link an unwinder into a fake library).
 		"-fno-unwind-tables",