[Frontend] Always output swiftdeps when allowing errors

A module is always output when allowing errors, make sure to output its
dependencies as well.

Author: bnbarham

lib/FrontendTool/FrontendTool.cpp

@@ -640,7 +640,10 @@ static void emitSwiftdepsForAllPrimaryInputsIfNeeded(
   //
   // FIXME: It seems more appropriate for the driver to notice the early-exit
   // and react by always enqueuing the jobs it dropped in the other waves.
-  if (Instance.getDiags().hadAnyError())
+  //
+  // We will output a module if allowing errors, so ignore that case.
+  if (Instance.getDiags().hadAnyError() &&
+      !Invocation.getFrontendOptions().AllowModuleWithCompilerErrors)
     return;
 
   for (auto *SF : Instance.getPrimarySourceFiles()) {

test/Frontend/allow-errors.swift

@@ -1,9 +1,12 @@
 // RUN: %empty-directory(%t)
 
 // The module should be generated regardless of errors and diagnostic should still be output
-// RUN: %target-swift-frontend -verify -emit-module -o %t/errors.swiftmodule -experimental-allow-module-with-compiler-errors -D ERROR_MODULE %s
+// RUN: %target-swift-frontend -verify -emit-module -o %t/errors.swiftmodule -emit-reference-dependencies-path %t/errors.swiftdeps -emit-dependencies-path %t/errors.d -experimental-allow-module-with-compiler-errors -D ERROR_MODULE -primary-file %s
 // RUN: llvm-bcanalyzer %t/errors.swiftmodule | %FileCheck -check-prefix=CHECK-BC %s
 // CHECK-BC-NOT: UnknownCode
+// RUN: ls %t/errors.swiftdeps
+// RUN: ls %t/errors.d
+
 #if ERROR_MODULE
 public struct ValidStructInvalidMember {
   public var member: String