Ninja: Simplify computation of GLOBAL_TARGET outputs

In cmGlobalNinjaGenerator::AppendTargetOutputs we previously
handled GLOBAL_TARGET outputs specially in order to avoid adding
directory components to the output.  However, this is not necessary
because cmNinjaTargetGenerator::New already filters out copies of
these targets that are not at the top level.  Instead we can simply
follow the same output computation code path as UTILITY targets.

Source/cmGlobalNinjaGenerator.cxx

@@ -867,6 +867,7 @@ void cmGlobalNinjaGenerator::AppendTargetOutputs(
       break;
     }
     case cmState::OBJECT_LIBRARY:
+    case cmState::GLOBAL_TARGET:
     case cmState::UTILITY: {
       std::string path =
         target->GetLocalGenerator()->GetCurrentBinaryDirectory() +
@@ -875,12 +876,6 @@ void cmGlobalNinjaGenerator::AppendTargetOutputs(
       break;
     }
 
-    case cmState::GLOBAL_TARGET:
-      // Always use the target in HOME instead of an unused duplicate in a
-      // subdirectory.
-      outputs.push_back(this->NinjaOutputPath(target->GetName()));
-      break;
-
     default:
       return;
   }