Add missing include to make testshortcode build on gcc:latest.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/testshortcode.cc

@@ -21,6 +21,7 @@
 
 #include <sys/time.h>
 #include <assert.h>
+#include <stdint.h>
 
 #include "shortcode.hh"