RFA: Use fixup_fallthru_exit_predecessor only for

[David Edelsohn]

>>>>> Joern Rennecke writes:

Joern> try_simplify_condjump uses can_fallthru to determine if one block precedes another.
Joern> This doesn't work any more when the latter block is the exit block.

	Thanks for tracking down and fixing the problem.

	Is there any way to determine whether there are other hidden
problems like this?

David