Bug#14527: Partitions: table unreadable if partition name = c-cedilla

sql_partition.cc:
  Changeing THD charset to utf8 when parsing a frm file.
partition_charset.test, partition_charset.result:
  new file

mysql-test/r/partition_charset.result

+drop table if exists t1;
+set names utf8;
+create table t1 (s1 int)
+partition by list (s1)
+(partition c values in (1),
+partition Ç values in (3));
+insert into t1 values (1),(3);
+select * from t1;
+s1
+1
+3
+flush tables;
+set names latin1;
+select * from t1;
+s1
+1
+3
+drop table t1;

mysql-test/t/partition_charset.test

+#
+# Test for character set related things in combination
+# with the partition storage engine
+# 
+-- source include/have_partition.inc
+
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+set names utf8;
+create table t1 (s1 int)
+  partition by list (s1)
+    (partition c values in (1),
+     partition Ç values in (3));
+insert into t1 values (1),(3);
+select * from t1;
+flush tables;
+set names latin1;
+select * from t1;
+drop table t1;

sql/sql_partition.cc

@@ -3630,11 +3630,13 @@ bool mysql_unpack_partition(THD *thd, const uchar *part_buf,
   Item *thd_free_list= thd->free_list;
   bool result= TRUE;
   partition_info *part_info;
+  CHARSET_INFO *old_character_set_client= thd->variables.character_set_client;
   LEX *old_lex= thd->lex;
   LEX lex;
   DBUG_ENTER("mysql_unpack_partition");
 
   thd->lex= &lex;
+  thd->variables.character_set_client= system_charset_info;
   lex_start(thd, part_buf, part_info_len);
   /*
     We need to use the current SELECT_LEX since I need to keep the
@@ -3760,6 +3762,7 @@ bool mysql_unpack_partition(THD *thd, const uchar *part_buf,
 end:
   thd->free_list= thd_free_list;
   thd->lex= old_lex;
+  thd->variables.character_set_client= old_character_set_client;
   DBUG_RETURN(result);
 }