Rename native-only terminal related functions.

Looking at target_terminal_inferior etc. in async mode, I realized
that the naming of the terminal_inferior, terminal_ours,
etc. functions doesn't really give a clue that they're meant for the
native target only.  This patch renames them.  There's already
child_terminal_info using the child_ prefix, and, they're most
prominently installed by inf-child.c, so I went with the child_
prefix.  I dropped "inferior" from a couple to make the name match the
corresponding target method.

Tested on x86_64 Fedora 17, and cross built for mingw.  I didn't test
gnu-nat.c, but I think the change is as obvious as it gets.  I grepped
the tree looking for other potential spots that would need adjustment
but this is all I found.  If something breaks, it should be trivial to
fix.

gdb/
2014-03-14  Pedro Alves  <palves@redhat.com>

	* inferior.h (terminal_ours_for_output): Rename to ...
	(child_terminal_ours_for_output): ... this.
	(terminal_save_ours): Rename to ...
	(child_terminal_save_ours): ... this.
	(terminal_ours): Rename to ...
	(child_terminal_ours): ... this.
	(terminal_inferior): Rename to ...
	(child_terminal_inferior): ... this.
	(terminal_init_inferior): Rename to ...
	(child_terminal_init_inferior): ... this.
	(terminal_init_inferior_with_pgrp): Rename to ...
	(child_terminal_init_inferior_with_pgrp): ... this.
	* inflow.c (terminal_init_inferior_with_pgrp): Rename to ...
	(child_terminal_init_with_pgrp): ... this.
	(terminal_save_ours): Rename to ...
	(child_terminal_save_ours): ... this.
	(terminal_init_inferior): Rename to ...
	(child_terminal_init): ... this.  Adjust.
	(terminal_inferior): Rename to ...
	(child_terminal_inferior): ... this.
	(terminal_ours_for_output): Rename to ...
	(child_terminal_ours_for_output): ... this.  Adjust.
	(terminal_ours): Rename to ...
	(child_terminal_ours): ... this.
	(terminal_ours_1): Rename to ...
	(child_terminal_ours_1): ... this.  Adjust.
	* linux-nat.c (linux_nat_terminal_inferior): Adjust.
	* windows-nat.c (do_initial_windows_stuff): Adjust.
	* gnu-nat.c (gnu_terminal_init_inferior): Rename to ...
	(gnu_terminal_init): ... this.  Adjust.
	(gnu_target): Adjust.
	* inf-child.c (inf_child_target): Adjust.