Include config.h as the first thing in every .c file

...except for CheckForAbstractSockets.c, which runs before config.h is
generated, and sd-daemon.c, which is externally-maintained.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=59971
Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Colin Walters <walters@verbum.org>

test/name-test/test-autolaunch.c

@@ -1,3 +1,5 @@
+#include "config.h"
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

test/test-exit.c

@@ -1,3 +1,5 @@
+#include "config.h"
+
 /* This is a process that just exits with a failure code */
 int
 main (int argc, char **argv)

tools/strtoll.c

@@ -27,6 +27,7 @@
  * SUCH DAMAGE.
  */
 
+#include "config.h"
 
 #include <limits.h>
 #ifdef HAVE_ERRNO_H

tools/strtoull.c

@@ -27,6 +27,7 @@
  * SUCH DAMAGE.
  */
 
+#include "config.h"
 
 #include <limits.h>
 #ifdef HAVE_ERRNO_H