exit upon failure does not work on VBCC Amiga

For some reason, using setjmp()/longjmp() fails when used on VBCC compiled code for classic 68k Amiga. The observed behavior is that it looks like the tests are hanging, and occasionally leading to a crash. My hunch is that setjmp/longjmp are broken, so I only use this on non-Amiga platforms, where it seems to work without problems.
