Heisenbugs in the test-suite

Hi all,

I'm getting some Heisenbugs in the test-suite, sometimes.

This is what their trace looks like:

This might be due to the port numbers being used with the debugserver. Right now we are grabbing a random port number in the valid user space port range and passing that down to debugserver as an argument for it to connect back up to lldb. The better way to do this, for local debug sessions, would be to open a port by binding to port zero and finding the port number, then passing an option to debugserver with the port number for debugserver to connect back to lldb.