util: split out signal-util.[ch] from util.[ch]

No functional changes.

src/network/networkd-wait-online.c

@@ -21,11 +21,10 @@
 #include <getopt.h>
 
 #include "sd-daemon.h"
-
-#include "networkd-wait-online.h"
-
 #include "strv.h"
 #include "build.h"
+#include "signal-util.h"
+#include "networkd-wait-online.h"
 
 static bool arg_quiet = false;
 static usec_t arg_timeout = 120 * USEC_PER_SEC;

src/network/networkd.c

@@ -19,9 +19,9 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include "capability.h"
 #include "sd-daemon.h"
-
+#include "capability.h"
+#include "signal-util.h"
 #include "networkd.h"
 
 int main(int argc, char *argv[]) {