Add missing #includes for standalone spherical-information-related headers

(cherry picked from commit f912fd76)
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/isom.h

@@ -24,6 +24,9 @@
 #ifndef AVFORMAT_ISOM_H
 #define AVFORMAT_ISOM_H
 
+#include <stddef.h>
+#include <stdint.h>
+
 #include "libavutil/spherical.h"
 #include "libavutil/stereo3d.h"
 

libavutil/spherical.h

@@ -26,6 +26,9 @@
 #ifndef AVUTIL_SPHERICAL_H
 #define AVUTIL_SPHERICAL_H
 
+#include <stddef.h>
+#include <stdint.h>
+
 /**
  * @addtogroup lavu_video
  * @{