pan/bi: Fix more jumps to terminal blocks

pan/bi: Fix more jumps to terminal blocks

Here's another edge case: there could be instructions in the last block
after NIR->BIR but they could be optimized out by backend DCE, causing
the block to become a terminal block.

Noticed while toying with geometry shaders.

Fixes: a805d999c0e ("pan/bi: Fix jumps to terminal block again")
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9137>