This testcase seems to assume the target is running Linux, so bare 
metal, simulators and other debugging stubs running different OS' will 
have a hard time executing some of the commands the testcase issues.

Even restricting the testcase to Linux systems (which the patch below 
does), there are still problems with, say, QEMU not providing PID 
information when "info inferior" is issued. As a consequence, the 
subsequent tests will either fail or will not make much sense.

The attached patch checks if PID information is available. If not, it 
just bails out and avoids running into a number of failures.

No regressions on x86-64. For QEMU, i see only a couple PASSes before it 
is done with the testcase.

OK?