do not use kernel headers' asm/page.h

http://bugs.gentoo.org/187083

--- libs/video/targets/vid_fbdev.c
+++ libs/video/targets/vid_fbdev.c
@@ -58,7 +58,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <asm/page.h>
+#define PAGE_MASK sysconf(_SC_PAGE_SIZE)
 #include <linux/kd.h>
 #include <linux/vt.h>
 #include <sys/stat.h>