all: include-what-you-see fixes

After uint32_t fix from 1e82461875
it was good idea to check which headers where needed where. And
generally clean up the includes while doing the check.

src/dhcpd-pools.c

@@ -33,24 +33,24 @@
  * official policies, either expressed or implied, of Sami Kerola.
  */
 
-#ifdef HAVE_CONFIG_H
 #include <config.h>
-#endif
 
-#include <stdio.h>
 #ifdef  HAVE_STDLIB_H
 #include <stdlib.h>
-#else				/* Not STDC_HEADERS */
+#else
 extern char *malloc();
-#endif				/* STDC_HEADERS */
+#endif
+
 #ifdef  HAVE_STRING_H
 #include <string.h>
 #else
 #include <strings.h>
 #endif
+
 #include <err.h>
 #include <errno.h>
 #include <getopt.h>
+#include <stdio.h>
 
 #include "defaults.h"
 #include "dhcpd-pools.h"