i965: fallback lineloop on sandybridge for now

Until we fixed GS hang issue.

src/mesa/drivers/dri/i965/brw_draw.c

@@ -204,6 +204,13 @@ static GLboolean check_fallbacks( struct brw_context *brw,
    GLcontext *ctx = &brw->intel.ctx;
    GLuint i;
 
+   /* XXX FIXME */
+   if (brw->intel.gen >= 6) {
+       for (i = 0; i < nr_prims; i++)
+	   if (prim[i].mode == GL_LINE_LOOP)
+	       return GL_TRUE;
+   }
+
    /* If we don't require strict OpenGL conformance, never 
     * use fallbacks.  If we're forcing fallbacks, always
     * use fallfacks.