change back driver change from previous commit

src/mesa/drivers/dri/i915tex/intel_context.c

@@ -289,9 +289,12 @@ static void
 intelCheckFrontUpdate(GLcontext * ctx)
 {
    struct intel_context *intel = intel_context(ctx);
-   /* can't use _ColorDrawBufferMask as its value
-      might change if a different drawable is bound! */
-   if (ctx->Color.DrawBuffer[0] == GL_FRONT_LEFT) {
+   /* rely on _ColorDrawBufferMask being kept up to date by mesa
+      even for window-fbos. */
+   /* not sure. Might need that for all masks including
+      BUFFER_BIT_FRONT_LEFT maybe? */
+   if (intel->ctx.DrawBuffer->_ColorDrawBufferMask[0] ==
+       BUFFER_BIT_FRONT_LEFT) {
       intelScreenPrivate *screen = intel->intelScreen;
       __DRIdrawablePrivate *dPriv = intel->driDrawable;
       if (screen->current_rotation != 0) {