Add unistd.h for usleep().

Signed-off-by: Thomas Klausner <wiz@NetBSD.org>
Reviewed-by: Connor Behan <connor.behan@gmail.com>

src/vb_i2c.c

@@ -2,6 +2,7 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <unistd.h>
 
 #include "osdef.h"
 #include "vgatypes.h"

src/xgi_accel.c

@@ -34,6 +34,7 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <unistd.h>
 
 #include "xf86.h"
 #include "xf86_OSproc.h"