check for xserver 1.9.4.901 to enable tiling by default

Previous xservers had a bug in the EXA code which caused
display corruption in some cases.

See:
https://bugs.freedesktop.org/show_bug.cgi?id=33929

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>

src/radeon_kms.c

@@ -677,8 +677,13 @@ Bool RADEONPreInit_KMS(ScrnInfoPtr pScrn, int flags)
 #ifdef EXA_MIXED_PIXMAPS
     /* don't enable tiling if accel is not enabled */
     if (!info->r600_shadow_fb) {
-	Bool colorTilingDefault = info->ChipFamily >= CHIP_FAMILY_R300 &&
+	Bool colorTilingDefault =
+#if XORG_VERSION_CURRENT >= XORG_VERSION_NUMERIC(1,9,4,901,0)
+	    info->ChipFamily >= CHIP_FAMILY_R300 &&
 	    info->ChipFamily <= CHIP_FAMILY_CAYMAN;
+#else
+	FALSE;
+#endif
 
 	if (info->ChipFamily >= CHIP_FAMILY_R600) {
 	    /* set default group bytes, overridden by kernel info below */