Add _arch_/_cpu_ to index_*/bit_* in x86 cpu-features.h

Add _arch_/_cpu_ to index_*/bit_* in x86 cpu-features.h

index_* and bit_* macros are used to access cpuid and feature arrays o
struct cpu_features.  It is very easy to use bits and indices of cpuid
array on feature array, especially in assembly codes.  For example,
sysdeps/i386/i686/multiarch/bcopy.S has

	HAS_CPU_FEATURE (Fast_Rep_String)

which should be

	HAS_ARCH_FEATURE (Fast_Rep_String)

We change index_* and bit_* to index_cpu_*/index_arch_* and
bit_cpu_*/bit_arch_* so that we can catch such error at build time.

	[BZ #19762]
	* sysdeps/unix/sysv/linux/x86_64/64/dl-librecon.h
	(EXTRA_LD_ENVVARS): Add _arch_ to index_*/bit_*.
	* sysdeps/x86/cpu-features.c (init_cpu_features): Likewise.
	* sysdeps/x86/cpu-features.h (bit_*): Renamed to ...
	(bit_arch_*): This for feature array.
	(bit_*): Renamed to ...
	(bit_cpu_*): This for cpu array.
	(index_*): Renamed to ...
	(index_arch_*): This for feature array.
	(index_*): Renamed to ...
	(index_cpu_*): This for cpu array.
	[__ASSEMBLER__] (HAS_FEATURE): Add and use field.
	[__ASSEMBLER__] (HAS_CPU_FEATURE)): Pass cpu to HAS_FEATURE.
	[__ASSEMBLER__] (HAS_ARCH_FEATURE)): Pass arch to HAS_FEATURE.
	[!__ASSEMBLER__] (HAS_CPU_FEATURE): Replace index_##name and
	bit_##name with index_cpu_##name and bit_cpu_##name.
	[!__ASSEMBLER__] (HAS_ARCH_FEATURE): Replace index_##name and
	bit_##name with index_arch_##name and bit_arch_##name.