Merge branch 'ninja_additional_clean_files_custom_target' into release-3.15

Merge-request: !3739

Source/cmNinjaNormalTargetGenerator.cxx

@@ -85,6 +85,7 @@ void cmNinjaNormalTargetGenerator::Generate()
     this->WriteLinkStatement();
   }
 
+  // Find ADDITIONAL_CLEAN_FILES
   this->AdditionalCleanFiles();
 }
 

Source/cmNinjaUtilityTargetGenerator.cxx

@@ -135,6 +135,9 @@ void cmNinjaUtilityTargetGenerator::Generate()
     gg->WriteBuild(this->GetBuildFileStream(), phonyBuild);
   }
 
+  // Find ADDITIONAL_CLEAN_FILES
+  this->AdditionalCleanFiles();
+
   // Add an alias for the logical target name regardless of what directory
   // contains it.  Skip this for GLOBAL_TARGET because they are meant to
   // be per-directory and have one at the top-level anyway.