cbfscomptool: fix display of time_t

Not all systems have sizeof(time_t) == sizeof(long), so
cast the delta here to a long to match the %ld format.

Change-Id: If235577fc35454ddb15043c5a543f614b6f16a9e
Signed-off-by: Mike Frysinger <vapier@chromium.org>
Reviewed-on: https://review.coreboot.org/19902
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/cbfstool/cbfscomptool.c

@@ -81,7 +81,7 @@ int benchmark()
 		clock_gettime(CLOCK_MONOTONIC, &t_e);
 		printf("compressing %d bytes to %d took %ld seconds\n",
 			bufsize, outsize,
-			t_e.tv_sec - t_s.tv_sec);
+			(long)(t_e.tv_sec - t_s.tv_sec));
 	}
 	free(data);
 	free(compressed_data);