Rename identical functions

amd64-linux-nat.c and i386-linux-nat.c contain a number of functions
which are identical but for prefix on their names.  This commit
renames all such functions to have the prefix x86_ instead of the
prefixes amd64_ or i386_ and updates all uses of those functions.
The now-identical x86_ functions will be pulled out to a separate
shared file in a later commit.

gdb/
2014-06-27  Gary Benson  <gbenson@redhat.com>

	* amd64-linux-nat.c (amd64_linux_dr_get): Renamed to
	x86_linux_dr_get.  All uses updated.
	(amd64_linux_dr_set): Renamed to
	x86_linux_dr_set.  All uses updated.
	(amd64_linux_dr_get_addr): Renamed to
	x86_linux_dr_get_addr.  All uses updated.
	(amd64_linux_dr_get_control): Renamed to
	x86_linux_dr_get_control.  All uses updated.
	(amd64_linux_dr_get_status): Renamed to
	x86_linux_dr_get_status.  All uses updated.
	(amd64_linux_dr_set_control): Renamed to
	x86_linux_dr_set_control.  All uses updated.
	(amd64_linux_dr_set_addr): Renamed to
	x86_linux_dr_set_addr.  All uses updated.
	(amd64_linux_prepare_to_resume): Renamed to
	x86_linux_prepare_to_resume.  All uses updated.
	(amd64_linux_new_thread): Renamed to
	x86_linux_new_thread.  All uses updated.
	(amd64_linux_new_fork): Renamed to
	x86_linux_new_fork.  All uses updated.
	(amd64_linux_child_post_startup_inferior): Renamed to
	x86_linux_child_post_startup_inferior.  All uses updated.
	(amd64_linux_enable_btrace): Renamed to
	x86_linux_enable_btrace.  All uses updated.
	(amd64_linux_disable_btrace): Renamed to
	x86_linux_disable_btrace.  All uses updated.
	(amd64_linux_teardown_btrace): Renamed to
	x86_linux_teardown_btrace.  All uses updated.
	(amd64_linux_read_btrace): Renamed to
	x86_linux_read_btrace.  All uses updated.
	* i386-linux-nat.c (i386_linux_dr_get): Renamed to
	x86_linux_dr_get.  All uses updated.
	(i386_linux_dr_set): Renamed to
	x86_linux_dr_set.  All uses updated.
	(i386_linux_dr_get_addr): Renamed to
	x86_linux_dr_get_addr.  All uses updated.
	(i386_linux_dr_get_control): Renamed to
	x86_linux_dr_get_control.  All uses updated.
	(i386_linux_dr_get_status): Renamed to
	x86_linux_dr_get_status.  All uses updated.
	(i386_linux_dr_set_control): Renamed to
	x86_linux_dr_set_control.  All uses updated.
	(i386_linux_dr_set_addr): Renamed to
	x86_linux_dr_set_addr.  All uses updated.
	(i386_linux_prepare_to_resume): Renamed to
	x86_linux_prepare_to_resume.  All uses updated.
	(i386_linux_new_thread): Renamed to
	x86_linux_new_thread.  All uses updated.
	(i386_linux_new_fork): Renamed to
	x86_linux_new_fork.  All uses updated.
	(i386_linux_child_post_startup_inferior): Renamed to
	x86_linux_child_post_startup_inferior.  All uses updated.
	(i386_linux_enable_btrace): Renamed to
	x86_linux_enable_btrace.  All uses updated.
	(i386_linux_disable_btrace): Renamed to
	x86_linux_disable_btrace.  All uses updated.
	(i386_linux_teardown_btrace): Renamed to
	x86_linux_teardown_btrace.  All uses updated.
	(i386_linux_read_btrace): Renamed to
	x86_linux_read_btrace.  All uses updated.
Merge {i386,amd64}_linux_read_description

This commit merges i386_ and amd64_linux_read_description, renaming
both to x86_linux_read_description.
Merge ps_get_thread_area

This commit adds a new helper, x86_linux_get_thread_area, to
hold the common parts of the ps_get_thread_area functions in
i386-linux-nat.c and amd64-linux-nat.c.
Pull out common parts of _initialize_{i386,amd64}_linux_nat

This commit adds two new helpers, x86_linux_create_target
and x86_linux_register_target, to hold the parts of
_initialize_i386_linux_nat and _initialize_amd64_linux_nat
which are common.
Comment and whitespace changes

This commit merges the comments and whitespace in the common
parts of i386-linux-nat.c and amd64-linux-nat.c.
Move duplicated code into new files

This commit moves the duplicated code in {i386,amd64}-linux-nat.c
into the new files x86-linux-nat.[ch].  Additionally, a new
file i386-linux-nat.h was required to expose a value required
by the 32-bit code in x86-linux-nat.c.
Tidy #include lists

This commit tidies up the #include lists in {i386,amd64}-linux-nat.c,
removing headers that are no longer required and reordering some lines
so that both files roughly match.  Additionally, an unused definition
was removed from the middle of the #include list in i386-linux-nat.c.