Stop performance testing if OPTIMIZED=1 build failed

* If the compiler OPTIMIZED=1 build fails, turn off compiler perf testing.
* If the runtime OPTIMIZED=1 build fails and it is a performance test run, it
  is a fatal error, so send the failure message and exit.
* Added the ability to exit on a fatal error back to mysystem after it was
  accidentally removed in a previous commit.

Tested by doing: nightly -debug -performance -notest
with and without things to warn about added to the compiler and runtime.
Oops, I missed the part about the $fatal logic being inadvertently removed before. Please ignore the above!