x86: Don't include <init-arch.h> in assembly codes

There is no need to include <init-arch.h> in assembly codes since all
x86 IFUNC selector functions are written in C.  Tested on i686 and
x86-64.  There is no code change in libc.so, ld.so and libmvec.so.

	* sysdeps/i386/i686/multiarch/bzero-ia32.S: Don't include
	<init-arch.h>.
	* sysdeps/x86_64/fpu/multiarch/svml_d_sin8_core-avx2.S: Likewise.
	* sysdeps/x86_64/fpu/multiarch/svml_s_expf16_core-avx2.S: Likewise.
	* sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S: Likewise.