Initial Enhanced REP MOVSB/STOSB (ERMS) support

The newer Intel processors support Enhanced REP MOVSB/STOSB (ERMS) which
has a feature bit in CPUID.  This patch adds the Enhanced REP MOVSB/STOSB
(ERMS) bit to x86 cpu-features.

	* sysdeps/x86/cpu-features.h (bit_cpu_ERMS): New.
	(index_cpu_ERMS): Likewise.
	(reg_ERMS): Likewise.

(cherry picked from commit 0791f91d)