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/sql_servers.h

@@ -16,8 +16,13 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */
 
+#include "my_global.h"                  /* uint */
 #include "slave.h" // for tables_ok(), rpl_filter
 
+class THD;
+typedef struct st_lex_server_options LEX_SERVER_OPTIONS;
+typedef struct st_mem_root MEM_ROOT;
+
 /* structs */
 typedef struct st_federated_server
 {