* enc/gbk.c: add GBK, CP936 and CP949.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@15308 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

enc/euc_cn.c

@@ -9,3 +9,4 @@ Init_euc_cn(void)
 }
 
 ENC_ALIAS("eucCN", "EUC-CN");
+ENC_ALIAS("GB2312", "EUC-CN");

enc/gb18030.c

@@ -493,6 +493,4 @@ OnigEncodingDefine(gb18030, GB18030) = {
   gb18030_left_adjust_char_head,
   gb18030_is_allowed_reverse_match
 };
-ENC_REPLICATE("GBK", "GB18030");
-ENC_REPLICATE("CP936", "GB18030");
-ENC_ALIAS("Windows-936", "GBK");
+