Move duplicated code into new files

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.

gdb/
2014-07-11  Gary Benson  <gbenson@redhat.com>

	* i386-linux-nat.h: New file.
	* x86-linux-nat.h: Likewise.
	* x86-linux-nat.c: Likewise.
	* Makefile.in (HFILES_NO_SRCDIR): Add the above new headers.
	* config/i386/linux.mh (NATDEPFILES): Add x86-linux-nat.o.
	* config/i386/linux64.mh (NATDEPFILES): Likewise.
	* amd64-linux-nat.c (x86-linux-nat.h): New include.
	(PTRACE_GETREGSET): Now in x86-linux-nat.h.
	(PTRACE_SETREGSET): Likewise.
	(arch_lwp_info): Now in x86-linux-nat.c.
	(have_ptrace_getregset): Now in x86-linux-nat.h.
	(x86_linux_dr_get): Now in x86-linux-nat.c.
	(x86_linux_dr_set): Likewise.
	(x86_linux_dr_get_addr): Likewise.
	(x86_linux_dr_get_control): Likewise.
	(x86_linux_dr_get_status): Likewise.
	(update_debug_registers_callback): Likewise.
	(x86_linux_dr_set_control): Likewise.
	(x86_linux_dr_set_addr): Likewise.
	(x86_linux_prepare_to_resume): Likewise.
	(x86_linux_new_thread): Likewise.
	(x86_linux_new_fork): Likewise.
	(x86_linux_get_thread_area): Likewise.
	(super_post_startup_inferior): Likewise.
	(x86_linux_child_post_startup_inferior): Likewise.
	(AMD64_LINUX_USER64_CS): Likewise.
	(AMD64_LINUX_X32_DS): Likewise.
	(x86_linux_read_description): Likewise.
	(x86_linux_enable_btrace): Likewise.
	(x86_linux_disable_btrace): Likewise.
	(x86_linux_teardown_btrace): Likewise.
	(x86_linux_read_btrace): Likewise.
	(x86_linux_create_target): Likewise.
	(x86_linux_add_target): Likewise.
	* i386-linux-nat.c (x86-linux-nat.h): New include.
	(PTRACE_GETREGSET): Now in x86-linux-nat.h.
	(PTRACE_SETREGSET): Likewise.
	(arch_lwp_info): Now in x86-linux-nat.c.
	(have_ptrace_getregset): Now in x86-linux-nat.h.
	(x86_linux_dr_get): Now in x86-linux-nat.c.
	(x86_linux_dr_set): Likewise.
	(x86_linux_dr_get_addr): Likewise.
	(x86_linux_dr_get_control): Likewise.
	(x86_linux_dr_get_status): Likewise.
	(update_debug_registers_callback): Likewise.
	(x86_linux_dr_set_control): Likewise.
	(x86_linux_dr_set_addr): Likewise.
	(x86_linux_prepare_to_resume): Likewise.
	(x86_linux_new_thread): Likewise.
	(x86_linux_new_fork): Likewise.
	(x86_linux_get_thread_area): Likewise.
	(super_post_startup_inferior): Likewise.
	(x86_linux_child_post_startup_inferior): Likewise.
	(AMD64_LINUX_USER64_CS): Likewise.
	(AMD64_LINUX_X32_DS): Likewise.
	(x86_linux_read_description): Likewise.
	(x86_linux_enable_btrace): Likewise.
	(x86_linux_disable_btrace): Likewise.
	(x86_linux_teardown_btrace): Likewise.
	(x86_linux_read_btrace): Likewise.
	(x86_linux_create_target): Likewise.
	(x86_linux_add_target): Likewise.