Fix implicit function declarations and open() mode bug.
--- xf86-video-xgi-1.6.1/src/xgi_driver.c.orig	2015-08-18 00:57:47.000000000 +0200
+++ xf86-video-xgi-1.6.1/src/xgi_driver.c	2015-09-06 09:57:48.143727372 +0200
@@ -68,13 +68,16 @@
 #include "mipointer.h"
 
 #include "xgi.h"
+#include "xgi_accel.h"
 #include "xgi_regs.h"
 #include "xgi_vb.h"
 #include "xgi_dac.h"
 #include "vb_def.h"
+#include "vb_ext.h"
 #include "xgi_driver.h"
 #include "valid_mode.h"
 #include "vb_i2c.h"
+#include "vb_setmode.h"
 
 #define _XF86DGA_SERVER_
 #include <X11/extensions/xf86dgaproto.h>
@@ -2797,7 +2800,7 @@
     FbDevExist = FALSE;
    if((pXGI->Chipset != PCI_CHIP_XGIXG20)&&(pXGI->Chipset != PCI_CHIP_XGIXG21)&&( pXGI->Chipset != PCI_CHIP_XGIXG27 ))
    {
-        if ((fd = open("/dev/fb", 'r')) != -1) {
+        if ((fd = open("/dev/fb", O_RDONLY)) != -1) {
             PDEBUG(ErrorF("--- open /dev/fb....   \n"));
             ioctl(fd, FBIOGET_FSCREENINFO, &fix);
             if (fix.accel == FB_ACCEL_XGI_GLAMOUR) {