Since INLINEASM_BR is a terminator we need to flush the pending exports before
emitting it. If we don't do this, a TokenFactor can be inserted between it and
the BR instruction emitted to finish the callbr lowering.
It looks like nodes are glued to the INLINEASM_BR so I had to make sure we emit
the TokenFactor before that.
Not sure if we should also flush PendingLoads for asm goto as well.
I'm also not sure how to directly write a test for this. I'm not sure how to get the TokenFactor to cause something to fail.