Added stdc_format_macros to err.

src/modules/systemlib/err.c

@@ -40,6 +40,9 @@
 
 #include <px4_config.h>
 
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>