* linux-nat.c (my_waitpid): New function.
(linux_test_for_tracefork): Make more robust and verbose. Take
an ORIGINAL_PID argument and test for PTRACE_SETOPTIONS first.
(linux_supports_tracefork, linux_supports_tracevforkdone): Take a PID
argument. Update calls to linux_test_for_tracefork.
(linux_enable_event_reporting, child_follow_fork)
(child_insert_fork_catchpoint, child_insert_vfork_catchpoint)
(child_insert_exec_catchpoint): Update calls to
linux_supports_tracefork and linux_supports_tracevforkdone.