[binutils-gdb] Introduce basic LWP accessors

[sergiodj+buildbot@redhat.com]

*** TEST RESULTS FOR COMMIT cff068da9d13bc9fa8c04f42151b4e92bfff86a1 ***

Author: Gary Benson <gbenson@redhat.com>
Branch: master
Commit: cff068da9d13bc9fa8c04f42151b4e92bfff86a1

Introduce basic LWP accessors
This commit introduces three accessors that shared Linux code can
use to access fields of struct lwp_info.  The GDB and gdbserver
Linux x86 code is modified to use them.

gdb/ChangeLog:

	* nat/linux-nat.h (ptid_of_lwp): New declaration.
	(lwp_is_stopped): Likewise.
	(lwp_stop_reason): Likewise.
	* linux-nat.c (ptid_of_lwp): New function.
	(lwp_is_stopped): Likewise.
	(lwp_is_stopped_by_watchpoint): Likewise.
	* x86-linux-nat.c (update_debug_registers_callback):
	Use lwp_is_stopped.
	(x86_linux_prepare_to_resume): Use ptid_of_lwp and
	lwp_stop_reason.

gdb/gdbserver/ChangeLog:

	* linux-low.c (ptid_of_lwp): New function.
	(lwp_is_stopped): Likewise.
	(lwp_stop_reason): Likewise.
	* linux-x86-low.c (update_debug_registers_callback):
	Use lwp_is_stopped.
	(x86_linux_prepare_to_resume): Use ptid_of_lwp and
	lwp_stop_reason.