Vector cosf for x86_64.

Vector cosf for x86_64.

Here is implementation of vectorized cosf containing SSE, AVX,
AVX2 and AVX512 versions according to Vector ABI
<https://groups.google.com/forum/#!topic/x86-64-abi/LmppCfN1rZ4>.

    * sysdeps/x86_64/fpu/Makefile (libmvec-support): Added new files.
    * sysdeps/x86_64/fpu/Versions: New versions added.
    * sysdeps/x86_64/fpu/svml_s_cosf4_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf4_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf4_core_sse4.S: New file.
    * sysdeps/x86_64/fpu/svml_s_cosf8_core_avx.S: New file.
    * sysdeps/x86_64/fpu/svml_s_cosf8_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf8_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf8_core_avx2.S: New file.
    * sysdeps/x86_64/fpu/svml_s_cosf16_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf16_core.S: New file.
    * sysdeps/x86_64/fpu/multiarch/svml_s_cosf16_core_avx512.S: New file.
    * sysdeps/x86_64/fpu/svml_s_wrapper_impl.h: New file.
    * sysdeps/x86_64/fpu/svml_s_cosf_data.S: New file.
    * sysdeps/x86_64/fpu/svml_s_cosf_data.h: New file.
    * sysdeps/x86_64/fpu/multiarch/Makefile (libmvec-sysdep_routines): Added
    build of SSE, AVX2 and AVX512 IFUNC versions.
    * sysdeps/unix/sysv/linux/x86_64/libmvec.abilist: New versions added.
    * sysdeps/x86/fpu/bits/math-vector.h: Added SIMD declaration for cosf.
    * NEWS: Mention addition of x86_64 vector cosf.