Option to disable printing package-name in public or private interface.

Having package-name flag in non-package interfaces causes them to be built as if
belonging to a package, which causes an issue for a loading client outside of the
package as follows.

For example, when building X that depends on A with the following dependency chain:
  X --> A --> B --(package-only)--> C

1. X itself is not in the same package as A, B, and C.
2. When dependency scanning X, and opening up B, because the scan target is in a
   different package domain, the scanner decides that B's package-only dependency
   on C is to be ignored.
3. When then finally building A itself, it will load its dependencies, but because
   the .private.swiftinterface of A still specifies -package-name, when it loads
   B, it will then examine its dependencies and deem that this package-only dependency
   on C is required.

Because (2) and (3) disagree, we get an error now when building the private A textual interface.

rdar://130701866

lib/Frontend/CompilerInvocation.cpp

@@ -459,6 +459,7 @@ static void ParseModuleInterfaceArgs(ModuleInterfaceOptions &Opts,
     Args.hasArg(OPT_debug_emit_invalid_swiftinterface_syntax);
   Opts.PrintMissingImports =
     !Args.hasArg(OPT_disable_print_missing_imports_in_module_interface);
+  Opts.DisablePackageNameForNonPackageInterface |= Args.hasArg(OPT_disable_print_package_name_for_non_package_interface);
 
   if (const Arg *A = Args.getLastArg(OPT_library_level)) {
     StringRef contents = A->getValue();