[fixes #1836] superbuilder didn’t play ball with field prefixes, at least in javac.

test/transform/resource/before/SuperBuilderWithPrefixes.java

@@ -0,0 +1,8 @@
+//CONF: lombok.accessors.prefix += m
+//CONF: lombok.accessors.prefix += x
+@lombok.experimental.SuperBuilder
+class SuperBuilderWithPrefixes {
+	int mField;
+	int xOtherField;
+	@lombok.Singular java.util.List<String> mItems;
+}