VMError::controlled_crash intentionally invokes undefined behavior

There are multiple places where VMError::controlled_crash (in utilities/vmError.cpp) intentionally invokes undefined behavior, in an attempt to provoke a crash that can be examined by a surrounding test driver. However, the compiler is free to generate pretty much anything at all for such manifest invocations of undefined behavior. Indeed, some of the test cases have comments suggesting that no crash might occur.

This function should be reworked to do something reliable, e.g. using raise() to generate the desired signal, and similar things. As it is, some of the tests it performs are pretty questionable.