avutil/error: Include macros.h for MKTAG

Up until now, including error.h alone does not make the AVERROR_* defines
usable, because they just expand to something involving MKTAG, but
without the header providing MKTAG. So include macros.h, the header
providing MKTAG.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavutil/error.h

@@ -27,6 +27,8 @@
 #include <errno.h>
 #include <stddef.h>
 
+#include "macros.h"
+
 /**
  * @addtogroup lavu_error
  *