Biarch support for i386/amd64 gdbserver.

	Biarch support for i386/amd64 gdbserver.
	* Makefile.in (SFILES): Remove linux-i386-low.c, linux-x86-64-low.c.
	Add linux-x86-low.c.
	(linux-i386-low.o, linux-x86-64-low.o): Delete.
	(linux-x86-low.o): Add.
	* linux-x86-64-low.c: Delete.
	* linux-i386-low.c: Delete.
	* linux-x86-low.c: New file.
	* configure.srv (i?86-linux srv_tgtobj): Replace linux-i386-low.o with
	linux-x86-low.o.
	(x86_64-linux srv_tgtobj): Replace linux-x86-64-low.o with
	linux-x86-low.o.
	(x86_64-linux srv_regobj): Add reg-i386-linux.o.
	* linux-low.c: Include ansidecl.h, elf/common.h, elf/external.h.
	(linux_child_pid_to_exec_file): New function.
	(elf_64_header_p, elf_64_file_p): New functions.
	(siginfo_fixup): New function.
	(linux_xfer_siginfo): New local inf_siginfo.  Call siginfo_fixup to
	give target a chance to convert layout.
	* linux-low.h (linux_target_ops): New member siginfo_fixup.
	(linux_child_pid_to_exec_file, elf_64_file_p): Declare.