i965: Disable register spilling on Ivybridge for now.

The data port messages for this are rather different.  For now, fail to
compile rather than hanging the GPU.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp

@@ -244,6 +244,8 @@ fs_visitor::assign_regs()
 
       if (reg == -1) {
 	 fail("no register to spill\n");
+      } else if (intel->gen >= 7) {
+	 fail("no spilling support on gen7 yet\n");
       } else if (c->dispatch_width == 16) {
 	 fail("no spilling support on 16-wide yet\n");
       } else {