Fix more warnings

main.c: In function 'term_handler':
main.c:54: warning: implicit declaration of function 'strsignal'

client.c: In function 'client_parse_xml':
client.c:248: warning: implicit declaration of function 'strcmp'

dbus_service.c: In function 'lashd_client_disconnect_handler':
dbus_service.c:107: warning: implicit declaration of function 'strcmp'

lashd/client.c

@@ -21,6 +21,7 @@
 
 #include "../config.h"
 
+#include <string.h>
 #include <dbus/dbus.h>
 
 #include "common/safety.h"

lashd/dbus_service.c

@@ -21,6 +21,7 @@
 
 #include "config.h"
 
+#include <string.h>
 #include <dbus/dbus.h>
 
 #include "dbus_service.h"

lashd/main.c

@@ -24,6 +24,7 @@
 
 #include "../config.h"
 
+#include <string.h>
 #include <getopt.h>
 #include <stdio.h>
 #include <stdlib.h>