* infrun.c (wait_for_inferior): When we hit a breakpoint for the
wrong thread, make sure to write the fixed PC value into the thread
that stopped. Restart all threads after single stepping over a
breakpoint for a different thread.
* breakpoint.c (set_momentary_breakpoint): Make momentary
breakpoints thread specific in a multi-threaded program.
* lynx-nat.c (child_resume): Add some comments. Correctly
choose between the single and multi-threaded step and continue
ptrace calls.
Some of the lynx-6100 single stepping fixes.