* linux-fork.c (linux_fork_detach): New.

	* linux-fork.c (linux_fork_detach): New.
	* linux-fork.h (linux_fork_detach): Declare.
	* linux-nat.c (linux_child_follow_fork): When following the fork
	child, add the child inferior before possibly detaching from the
	parent.  Don't reinstall ourselves.
	(linux_nat_detach): Call linux_fork_detach if there are other
	forks to debug.
	* linux-thread-db.c (thread_db_detach): Don't call
	target_mourn_inferior.  Instead inline the necessary bits.
	* inf-ptrace.c (inf_ptrace_detach): Don't unpush the target if
	there are other inferiors to debug.