Remove Ruby to_hash methods

ruby/ext/google/protobuf_c/map.c

@@ -847,7 +847,6 @@ void Map_register(VALUE module) {
   rb_define_method(klass, "dup", Map_dup, 0);
   rb_define_method(klass, "==", Map_eq, 1);
   rb_define_method(klass, "hash", Map_hash, 0);
-  rb_define_method(klass, "to_hash", Map_to_h, 0);
   rb_define_method(klass, "to_h", Map_to_h, 0);
   rb_define_method(klass, "inspect", Map_inspect, 0);
   rb_define_method(klass, "merge", Map_merge, 1);

ruby/ext/google/protobuf_c/message.c

@@ -737,7 +737,6 @@ VALUE build_class_from_descriptor(Descriptor* desc) {
   rb_define_method(klass, "eql?", Message_eq, 1);
   rb_define_method(klass, "hash", Message_hash, 0);
   rb_define_method(klass, "to_h", Message_to_h, 0);
-  rb_define_method(klass, "to_hash", Message_to_h, 0);
   rb_define_method(klass, "inspect", Message_inspect, 0);
   rb_define_method(klass, "to_s", Message_inspect, 0);
   rb_define_method(klass, "[]", Message_index, 1);

ruby/src/main/java/com/google/protobuf/jruby/RubyMap.java

@@ -338,7 +338,7 @@ public class RubyMap extends RubyObject {
         return newMap;
     }
 
-    @JRubyMethod(name = {"to_h", "to_hash"})
+    @JRubyMethod(name = "to_h")
     public RubyHash toHash(ThreadContext context) {
         return RubyHash.newHash(context.runtime, table, context.runtime.getNil());
     }

ruby/src/main/java/com/google/protobuf/jruby/RubyMessage.java

@@ -368,7 +368,7 @@ public class RubyMessage extends RubyObject {
         return ret;
     }
 
-    @JRubyMethod(name = {"to_h", "to_hash"})
+    @JRubyMethod(name = "to_h")
     public IRubyObject toHash(ThreadContext context) {
         Ruby runtime = context.runtime;
         RubyHash ret = RubyHash.newHash(runtime);