cangen: explicitly include <getopt.h>

getopt was being pulled in indirectly via the other headers.
We use it, thus include it directly instead.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

cangen.c

@@ -53,6 +53,7 @@
 #include <libgen.h>
 #include <time.h>
 #include <errno.h>
+#include <getopt.h>
 
 #include <sys/time.h>
 #include <sys/types.h>