WL#5030: Split and remove mysql_priv.h

This patch:

- Moves all definitions from the mysql_priv.h file into
  header files for the component where the variable is
  defined
- Creates header files if the component lacks one
- Eliminates all include directives from mysql_priv.h
- Eliminates all circular include cycles
- Rename time.cc to sql_time.cc
- Rename mysql_priv.h to sql_priv.h

sql/key.h

@@ -0,0 +1,39 @@
+/* Copyright 2006-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */
+
+#ifndef KEY_INCLUDED
+#define KEY_INCLUDED
+
+#include "my_global.h"                          /* uchar */
+
+class Field;
+class String;
+struct TABLE;
+typedef struct st_bitmap MY_BITMAP;
+typedef struct st_key KEY;
+typedef struct st_key_part_info KEY_PART_INFO;
+
+int find_ref_key(KEY *key, uint key_count, uchar *record, Field *field,
+                 uint *key_length, uint *keypart);
+void key_copy(uchar *to_key, uchar *from_record, KEY *key_info, uint key_length);
+void key_restore(uchar *to_record, uchar *from_key, KEY *key_info,
+                 uint key_length);
+bool key_cmp_if_same(TABLE *form,const uchar *key,uint index,uint key_length);
+void key_unpack(String *to,TABLE *form,uint index);
+bool is_key_used(TABLE *table, uint idx, const MY_BITMAP *fields);
+int key_cmp(KEY_PART_INFO *key_part, const uchar *key, uint key_length);
+extern "C" int key_rec_cmp(void *key_info, uchar *a, uchar *b);
+
+#endif /* KEY_INCLUDED */