Remove any assumption that a wait syscall on a thread id after a
continue will return. Any time we continue a thread, wait for activity
from any thread, because the scheduler may well have switched contexts
on us due to syscall entrace, channel op, etc...
There are several more things to be done here including:
* Potential tracking of goroutine id as we jump around to thread
contexts.
* Potential of selectively choosing threads to operate on based on the
internal M data structures, ensuring that our M has an active G.
This commit partially fixes#23 and #24, however there are still some
random hangs that happen and need to be ironed out.
Once the program detects that we have stepped into another function,
we simply calculate the return address and then set a breakpoint and
continue to that location, avoiding numerous syscalls.
