Use HAS_ARCH_FEATURE with Fast_Rep_String

HAS_ARCH_FEATURE, not HAS_CPU_FEATURE, should be used with
Fast_Rep_String.

	[BZ #19762]
	* sysdeps/i386/i686/multiarch/bcopy.S (bcopy): Use
	HAS_ARCH_FEATURE with Fast_Rep_String.
	* sysdeps/i386/i686/multiarch/bzero.S (__bzero): Likewise.
	* sysdeps/i386/i686/multiarch/memcpy.S (memcpy): Likewise.
	* sysdeps/i386/i686/multiarch/memcpy_chk.S (__memcpy_chk):
	Likewise.
	* sysdeps/i386/i686/multiarch/memmove_chk.S (__memmove_chk):
	Likewise.
	* sysdeps/i386/i686/multiarch/mempcpy.S (__mempcpy): Likewise.
	* sysdeps/i386/i686/multiarch/mempcpy_chk.S (__mempcpy_chk):
	Likewise.
	* sysdeps/i386/i686/multiarch/memset.S (memset): Likewise.
	* sysdeps/i386/i686/multiarch/memset_chk.S (__memset_chk):
	Likewise.

(cherry picked from commit 4e940b2f)