Don't put glyphs pixmaps into buffer objects under uxa.

in the fastpath they're going straight to the glyph cache anyway and
doing so for small glyphs wastes memory since bos must be padded to page
size.

Backport from upstream (to aid gem development). ok matthieu@

driver/xf86-video-intel/src/i830_exa.c

@@ -945,6 +945,9 @@ i830_uxa_create_pixmap (ScreenPtr screen, int w, int h, int depth, unsigned usag
 	return NullPixmap;
 
 #ifdef SERVER_1_5
+    if (usage == CREATE_PIXMAP_USAGE_GLYPH_PICTURE)
+        return fbCreatePixmap (screen, w, h, depth, usage);
+
     pixmap = fbCreatePixmap (screen, 0, 0, depth, usage);
 #else
     pixmap = fbCreatePixmap (screen, 0, 0, depth);