WL#5030: Splitting mysql_priv.h

Adding my_global.h first in all files using
NO_EMBEDDED_ACCESS_CHECKS.

Correcting a merge problem resulting from a changed definition
of check_some_access compared to the original patches.

sql/sql_prepare.cc

@@ -83,6 +83,7 @@ When one supplies long data for a placeholder:
     at statement execute.
 */
 
+#include "my_global.h"                          /* NO_EMBEDDED_ACCESS_CHECKS */
 #include "sql_priv.h"
 #include "unireg.h"
 #include "sql_class.h"                          // set_var.h: THD