ld/testsuite/

ld/testsuite/
	* ld-elf/eh1.d: Add explicit --64 to as options, and explicit
	-melf_x86_64 and -Ttext to ld options, so we don't assume every
	x86_64-*-* target uses --64 (vs --x32) by default or has the
	same address space layout.
	* ld-elf/eh2.d: Likewise.
	* ld-elf/eh3.d: Likewise.
	* ld-elf/eh4.d: Likewise.
	* ld-elf/elf.exp: For target *-*-nacl*, use options_regsub(ld) to
	map -melf_x86_64 to -melf_x86_64_nacl.