Provide crypto_cpu_caps_init() for amd64.

Provide crypto_cpu_caps_init() for amd64.

This is a CPU capability detection implementation in C, with minimal
inline assembly (for cpuid and xgetbv). This replaces the assembly
mess generated by x86_64cpuid.pl. Rather than populating OPENSSL_ia32cap_P
directly with CPUID output, just set the bits that the remaining
perlasm checks (namely AESNI, AVX, FXSR, INTEL, HT, MMX, PCLMUL, SSE, SSE2
and SSSE3).

ok joshua@ tb@