configure: Remove a xcb-dri2 leftover

Fixes compositor and clients trying to link against xcb-dri2.

configure.ac

@@ -108,11 +108,6 @@ if test "x$GCC" = "xyes"; then
 fi
 AC_SUBST(GCC_CFLAGS)
 
-# workaround a bug in xcb-dri2 generated by xcb-proto 1.6
-AC_CHECK_LIB(xcb-dri2, xcb_dri2_connect_alignment_pad, [],
-	     [AC_DEFINE([XCB_DRI2_CONNECT_DEVICE_NAME_BROKEN], [1],
-			[Define to 1 if xcb_dri2_connect_device_name is broken])])
-
 WAYLAND_SCANNER_RULES(['$(top_srcdir)/protocol'])
 
 AC_CONFIG_FILES([Makefile