* linux-fork.c: Include "gdb_assert.h".

	* linux-fork.c: Include "gdb_assert.h".
	(fork_load_infrun_state): Set inferior_ptid and stop_pc here.
	Update the register cache and selected frame also.
	(linux_fork_mourn_inferior): Use fork_load_infrun_state.  Return
	to single fork mode if necessary.
	(linux_fork_context): Remove bits handled by fork_load_infrun_state.
	* Makefile.in (linux_fork_h): New.
	(linux-fork.o, linux-nat.o): Update.