Bug#18004 Connecting crashes server when default charset is UCS2

table.cc:
  Fixing to use system_charset_info instead of default_charset_info.
  Crash happened because the "ctype" array is empty in UCS2,
  and thus cannot be used with my_isspace().
  The reason why UCS2 appeared in this context was because of
  of default_charset_info variable incorrectly substituted to my_isspace().
  As functions check_db_name(), check_table_name() and check_column_name()
  always get values in utf8, system_charset_info must be used instead.
ctype_ucs2_def.test, ctype_ucs2_def-master.opt, ctype_ucs2_def.result:
  new file

mysql-test/r/ctype_ucs2_def.result

+show variables like "%character_set_ser%";
+Variable_name	Value
+character_set_server	ucs2
+DROP TABLE IF EXISTS t1;
+create table t1 (a int);
+drop table t1;

mysql-test/t/ctype_ucs2_def-master.opt

+--default-character-set=ucs2 --default-collation=ucs2_unicode_ci

mysql-test/t/ctype_ucs2_def.test

+#
+# Bug#18004 Connecting crashes server when default charset is UCS2
+#
+show variables like "%character_set_ser%";
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+create table t1 (a int);
+drop table t1;

sql/table.cc

@@ -1423,7 +1423,7 @@ bool check_db_name(char *name)
   while (*name)
   {
 #if defined(USE_MB) && defined(USE_MB_IDENT)
-    last_char_is_space= my_isspace(default_charset_info, *name);
+    last_char_is_space= my_isspace(system_charset_info, *name);
     if (use_mb(system_charset_info))
     {
       int len=my_ismbchar(system_charset_info, name, 
@@ -1469,7 +1469,7 @@ bool check_table_name(const char *name, uint length)
   while (name != end)
   {
 #if defined(USE_MB) && defined(USE_MB_IDENT)
-    last_char_is_space= my_isspace(default_charset_info, *name);
+    last_char_is_space= my_isspace(system_charset_info, *name);
     if (use_mb(system_charset_info))
     {
       int len=my_ismbchar(system_charset_info, name, end);
@@ -1500,7 +1500,7 @@ bool check_column_name(const char *name)
   while (*name)
   {
 #if defined(USE_MB) && defined(USE_MB_IDENT)
-    last_char_is_space= my_isspace(default_charset_info, *name);
+    last_char_is_space= my_isspace(system_charset_info, *name);
     if (use_mb(system_charset_info))
     {
       int len=my_ismbchar(system_charset_info, name,