Add missing syscall.h include to utils.h

src/lxc/utils.h

@@ -25,6 +25,7 @@
 
 #include <errno.h>
 #include <stdarg.h>
+#include <sys/syscall.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include "config.h"