This patch removes a bunch of superfluous #include directives: if

postgres.h or c.h includes a system header (such as stdio.h or
stdlib.h), there's no need to specifically include it in any of the .c
files in the backend.

Neil Conway

src/backend/regex/regexec.c

@@ -46,7 +46,6 @@
  * macros that code uses.  This lets the same code operate on two different
  * representations for state sets.
  */
-#include <sys/types.h>
 #include <limits.h>
 #include <ctype.h>
 #include <assert.h>