Remove the config.h kludge and override vasprintf detection via HAVE_VASPRINTF.

lib/util.c

@@ -27,10 +27,6 @@
 # define _GNU_SOURCE	/* for vasprintf(3) */
 #endif
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
-
 #include <stdio.h>
 #include <stdbool.h>
 #include <stdlib.h>