Update libmvec multiarch functions for <cpu-features.h>

Update libmvec multiarch functions for <cpu-features.h>

This patch updates libmvec multiarch functions to use the newly defined
HAS_CPU_FEATURE, HAS_ARCH_FEATURE and LOAD_RTLD_GLOBAL_RO_RDX from
<cpu-features.h>.

	* math/Makefile ($(addprefix $(objpfx), $(libm-vec-tests))):
	Remove $(objpfx)init-arch.o.
	* sysdeps/x86_64/fpu/Makefile (libmvec-support): Remove
	init-arch.
	* sysdeps/x86_64/fpu/math-tests-arch.h (avx_usable): Removed.
	(INIT_ARCH_EXT): Defined as empty.
	(CHECK_ARCH_EXT): Replace HAS_XXX with HAS_ARCH_FEATURE (XXX).
	* sysdeps/x86_64/fpu/multiarch/svml_d_cos2_core.S: Remove
	__init_cpu_features call.  Replace HAS_XXX with
	HAS_CPU_FEATURE/HAS_ARCH_FEATURE (XXX).
	* sysdeps/x86_64/fpu/multiarch/svml_d_cos4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_cos8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_exp2_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_exp4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_exp8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_log2_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_log4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_log8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_pow2_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_pow4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_pow8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sin2_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sin4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sin8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sincos2_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sincos4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sincos8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_cosf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_cosf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_cosf8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_expf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_expf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_expf8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_logf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_logf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_logf8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_powf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_powf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_powf8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sincosf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sincosf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sincosf8_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sinf16_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sinf4_core.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_sinf8_core.S: Likewise.