STYLE: incorrect option name handling for foamCreateModuleInclude

- The usage claimed '-output=', but was using '--output=' for the
  output file.  Rectify to use single dash as documented.

bin/tools/foamCreateModuleInclude

@@ -85,10 +85,10 @@ do
     --recursive-backend--)
         optBackend=true
         ;;
-    --output=*)
+    -output=*)
         moduleOutput="${1#*=}"
         ;;
-    --tmpdir=*)
+    -tmpdir=*)
         moduleTmpDir="${1#*=}"
         ;;
     -*)