Enable AMD64 Serpent implementations on WIN64
* cipher/serpent-avx2-amd64.S: Enable when HAVE_COMPATIBLE_GCC_WIN64_PLATFORM_AS defined. (ELF): New macro to mask lines with ELF specific commands. * cipher/serpent-sse2-amd64.S: Enable when HAVE_COMPATIBLE_GCC_WIN64_PLATFORM_AS defined. (ELF): New macro to mask lines with ELF specific commands. * cipher/chacha20.c (USE_SSE2, USE_AVX2): Enable when HAVE_COMPATIBLE_GCC_WIN64_PLATFORM_AS defined. [USE_SSE2 || USE_AVX2] (ASM_FUNC_ABI): New. (_gcry_serpent_sse2_ctr_enc, _gcry_serpent_sse2_cbc_dec) (_gcry_serpent_sse2_cfb_dec, _gcry_serpent_avx2_ctr_enc) (_gcry_serpent_avx2_cbc_dec, _gcry_serpent_avx2_cfb_dec): Add ASM_FUNC_ABI.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>