init.c: Add missing #include

As required by PRIx8.

src/terrain/src/init.c

@@ -1,6 +1,7 @@
 #include <terrain.h>
 #include <ctype.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>