Taken from upstream bug tracker:
https://bugs.freedesktop.org/show_bug.cgi?id=72126

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>

diff -up xorg-server-1.14.4/hw/xfree86/common/compiler.h xorg-server-1.14.4-fix/hw/xfree86/common/compiler.h
--- xorg-server-1.14.4/hw/xfree86/common/compiler.h	2013-07-26 01:14:32.000000000 -0400
+++ xorg-server-1.14.4-fix/hw/xfree86/common/compiler.h	2013-11-27 23:16:46.000000000 -0500
@@ -727,7 +727,7 @@ xf86WriteMmio32LeNB(__volatile__ void *b
 #define PORT_SIZE short
 #endif
 
-_X_EXPORT unsigned int IOPortBase;      /* Memory mapped I/O port area */
+_X_EXPORT uintptr_t IOPortBase;      /* Memory mapped I/O port area */
 
 static __inline__ void
 outb(unsigned PORT_SIZE port, unsigned char val)
