build: add missing stdlib include to fix the build

ext/faac/gstfaac.c

@@ -47,6 +47,7 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <stdlib.h>
 #include <string.h>
 
 #include "gstfaac.h"

gst/videomeasure/gstvideomeasure_ssim.c

@@ -55,6 +55,7 @@
 #include "gstvideomeasure.h"
 #include "gstvideomeasure_ssim.h"
 #include <gst/audio/audio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <math.h>
 

tests/examples/camerabin/gst-camera-perf.c

@@ -56,6 +56,7 @@
 #ifdef SAVE_SNAPSHOT
 #include <gdk-pixbuf/gdk-pixbuf.h>
 #endif
+#include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
 #include <time.h>