Add a dummy option for GL acceleration to pass the configure when there is no
GL acceleration patch. The parsing function will be filled by following
opengl-disable-option.patch.

Upstream-Status: Inappropriate [other] - depends on GL patch

Signed-off-by: Zhai Edwin <edwin.zhai@intel.com>

Index: qemu-0.15.1/configure
===================================================================
--- qemu-0.15.1.orig/configure	2012-05-14 21:23:34.000000000 +0800
+++ qemu-0.15.1/configure	2012-05-14 21:23:36.000000000 +0800
@@ -179,6 +179,7 @@
 smartcard_nss=""
 usb_redir=""
 opengl=""
+gl_accel="yes"
 guest_agent="yes"
 
 # parse CC options first
@@ -739,6 +740,10 @@
   ;;
   --enable-opengl) opengl="yes"
   ;;
+  --disable-gl-accel) gl_accel="no"
+  ;;
+  --enable-gl-accel) gl_accel="yes"
+  ;;
   --*dir)
   ;;
   --disable-rbd) rbd="no"