Fix fail!() macros by utilizing zero cost exception support in the NaCl SDK.
Note this requires Pepper 34 or later. Additionally, it isn't supported
in stable pexes yet, so translation is required for all programs.
This fixes quite a large number of tests.

I've removed the passes that lower exception handling calls (invokes),
instead opting to leave that detail to the toolchain. Later on, when
we decide to add support for outputing linked pexe's directly (something
that would *greatly* sortin testing times), this will have to be readdressed.