* configure.in: Add support for x86_64 and x86_64-*-linux-gnu*

	* configure.in: Add support for x86_64 and x86_64-*-linux-gnu*
	* NEWS: Add x86_64.

	* i386.h (i386_optab): Add "rex*" instructions;
	add swapgs; disable jmp/call far direct instructions for
	64bit mode; add syscall and sysret; disable registers for 0xc6
	template.  Add 'q' suffixes to extendable instructions, disable
	obsoletted instructions, add new sign/zero extension ones.
	(i386_regtab): Add extended registers.
	(*Suf): Add No_qSuf.
	(q_Suf, wlq_Suf, bwlq_Suf): New.