KWSys: Avoid Clang optimizer bug in testProcess-[45]

Clang's optimizer, as of clang version 2.8 (trunk 107463), produces the
undefined instruction 'ud2' for the code "*(int*)0=0" on OS X x86_64.
It causes our crash tests to fail because the child process exits with
an invalid instruction instead of a segmentation fault.  Work around the
bug by using "*(int*)1=0" in this case.