tools: always include config.h before anything else.

Otherwise, _GNU_SOURCE isn't defined (for example) so prototypes such as
isblank can be missing.

tools/ccanlint/ccanlint.h

 #ifndef CCAN_LINT_H
 #define CCAN_LINT_H
+#include "config.h"
 #include <ccan/list/list.h>
 #include <stdbool.h>
 #include "../doc_extract.h"

tools/depends.c

-#include <ccan/talloc/talloc.h>
 #include <ccan/str/str.h>
+#include <ccan/talloc/talloc.h>
 #include <ccan/grab_file/grab_file.h>
 #include <ccan/str_talloc/str_talloc.h>
 #include <ccan/read_write_all/read_write_all.h>

tools/doc_extract-core.c

 /* This merely extracts, doesn't do XML or anything. */
+#include <ccan/talloc/talloc.h>
+#include <ccan/str/str.h>
+#include <ccan/str_talloc/str_talloc.h>
 #include <err.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -9,9 +12,6 @@
 #include <fcntl.h>
 #include <stdbool.h>
 #include <ctype.h>
-#include <ccan/talloc/talloc.h>
-#include <ccan/str/str.h>
-#include <ccan/str_talloc/str_talloc.h>
 #include "doc_extract.h"
 #include "tools.h"