Review fix for BUG#17015: Routine name truncation not an error

sql/field.h:
  Added new method to Field class: char_length()
sql/sp.cc:
  Use Field::char_length() to check number of characters in the name field.

sql/field.h

@@ -319,6 +319,12 @@ public:
   /* convert decimal to longlong with overflow check */
   longlong convert_decimal2longlong(const my_decimal *val, bool unsigned_flag,
                                     int *err);
+  /* The max. number of characters */
+  inline uint32 Field::char_length() const
+  {
+    return field_length / charset()->mbmaxlen;
+  }
+
   friend bool reopen_table(THD *,struct st_table *,bool);
   friend int cre_myisam(my_string name, register TABLE *form, uint options,
 			ulonglong auto_increment_value);

sql/sp.cc

@@ -509,11 +509,10 @@ db_create_routine(THD *thd, int type, sp_head *sp)
       goto done;
     }
 
-    if ((system_charset_info->cset->numchars(system_charset_info,
+    if (system_charset_info->cset->numchars(system_charset_info,
                                             sp->m_name.str,
-                                             sp->m_name.str+sp->m_name.length) *
-         table->field[MYSQL_PROC_FIELD_NAME]->charset()->mbmaxlen) >
-        table->field[MYSQL_PROC_FIELD_NAME]->field_length)
+                                            sp->m_name.str+sp->m_name.length) >
+        table->field[MYSQL_PROC_FIELD_NAME]->char_length())
     {
       ret= SP_BAD_IDENTIFIER;
       goto done;