include <sys/types.h> in xf86drmMode when the OS is FreeBSD

<sys/types.h> need to be included in xf86drmMode.c for type u_int in
<sys/sysctl.h> (that is included when OS is FreeBSD) to be recognized.

Signed-off-by: Eleni Maria Stea <elene.mst@gmail.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>

xf86drmMode.c

@@ -38,6 +38,9 @@
 #include <stdlib.h>
 #include <sys/ioctl.h>
 #if HAVE_SYS_SYSCTL_H
+#ifdef __FreeBSD__
+#include <sys/types.h>
+#endif
 #include <sys/sysctl.h>
 #endif
 #include <stdio.h>