WL#1324 table name to file name encoding

- Encoding itself, implemented as a charset
  "filename". Originally planned to use '.'
  as an escape character, but now changed to '@'
  for two reasons: "ls" does not return
  file names starting with '.' considering them
  as a kind of hidden files; some platforms
  do not allow several dots in a file name.
- replacing many calls of my_snprintf() and
  strnxmov() to the new build_table_filename().
- Adding MY_APPEND_EXT mysys flag, to append
  an extention rather that replace it.
- Replacing all numeric constants in fn_format
  flag arguments to their mysys definitions, e.g.
  MY_UNPACK_FILENAME,
- Predictability in several function/methods:
  when a table name can appear with or withot .frm
  extension. Some functions/methods were changed
  so accept names strictly with .frm, other - strictly
  without .frm extensions. Several DBUG_ASSERTs were
  added to check whether an extension is passed.
Many files:
  table name to file name encoding
mysql_priv.h:
  Prototypes for new table name encoding tools.
ctype-utf8.c:
  Implementing "filename" charset for
  table name to file name encoding.
row0mysql.c:
  Fixing table name prefix.
mf_format.c:
  Adding MY_APPEND_EXT processing.
Many files:
  Fixing tests.
my_sys.h:
  Adding new flag to append rather than replace an extension.
m_ctype.h:
  Adding "filename" charset definition.

sql/sql_acl.cc

@@ -2796,9 +2796,10 @@ bool mysql_table_grant(THD *thd, TABLE_LIST *table_list,
       if (!(rights & CREATE_ACL))
       {
         char buf[FN_REFLEN];
-        sprintf(buf,"%s/%s/%s.frm",mysql_data_home, table_list->db,
-                table_list->table_name);
-        fn_format(buf,buf,"","",4+16+32);
+        build_table_filename(buf, sizeof(buf), table_list->db,
+                             table_list->table_name, reg_ext);
+        fn_format(buf, buf, "", "", MY_UNPACK_FILENAME  | MY_RESOLVE_SYMLINKS |
+                                    MY_RETURN_REAL_PATH | MY_APPEND_EXT);
         if (access(buf,F_OK))
         {
           my_error(ER_NO_SUCH_TABLE, MYF(0), table_list->db, table_list->alias);