kfreebsd-gnu.h: Resync with `config/i386/linux.h'.

kfreebsd-gnu.h: Resync with `config/i386/linux.h'.

	* config/i386/kfreebsd-gnu.h: Resync with `config/i386/linux.h'.
	* config/kfreebsd-gnu.h (GNU_USER_DYNAMIC_LINKER): Resync with
	`config/linux.h'.

	* config/i386/kfreebsd-gnu64.h: New file.
	* config.gcc (x86_64-*-kfreebsd*-gnu): Replace `i386/kfreebsd-gnu.h'
	with `i386/kfreebsd-gnu64.h'.

	* config/i386/linux64.h (GNU_USER_LINK_EMULATION32)
	(GNU_USER_LINK_EMULATION64): New macros.
	* config/i386/gnu-user64.h (LINK_SPEC): Rely on
	`GNU_USER_LINK_EMULATION32' and `GNU_USER_LINK_EMULATION64' instead
	of hardcoding `elf_i386' and `elf_x86_64'.

From-SVN: r175031