Add an include for signal.h when needed

On Linux, signal.h is not required to have access to the signal
constants. On FreeBSD, this is not the case and requires signal.h to be
explicitly included.

This patch adds an include for signal.h in any source file that uses it.

Signed-off-by: Mark Weiman <mark.weiman@markzz.com>
Signed-off-by: Allan McRae <allan@archlinux.org>

lib/libalpm/util.c

@@ -33,6 +33,7 @@
 #include <sys/socket.h>
 #include <fnmatch.h>
 #include <poll.h>
+#include <signal.h>
 
 /* libarchive */
 #include <archive.h>

src/pacman/conf.c

@@ -31,6 +31,7 @@
 #include <sys/utsname.h> /* uname */
 #include <sys/wait.h>
 #include <unistd.h>
+#include <signal.h>
 
 /* pacman */
 #include "conf.h"