Fix deobfuscator not regenerating super maps (#4856)

src/main/java/net/minecraftforge/fml/common/asm/transformers/deobf/FMLDeobfuscatingRemapper.java

@@ -450,7 +450,7 @@ public class FMLDeobfuscatingRemapper extends Remapper {
         // generate maps for all parent objects
         for (String parentThing : allParents)
         {
-            if (!methodNameMaps.containsKey(parentThing))
+            if (!fieldNameMaps.containsKey(parentThing))
             {
                 findAndMergeSuperMaps(parentThing);
             }