Export CPU feature detection functions

[shibatch]

The following CPU feature detection functions will be implemented in common.c and exported. Each function returns non-zero value if the corresponding CPU feature is available. Sleef_cpuSupportsSVE() returns the value returned by svcntd() if SVE is available.

• Generic
  • int Sleef_cpuSupports128()
  • int Sleef_cpuSupports256()
  • int Sleef_cpuSupports512()
• x86
  • int Sleef_cpuSupportsSSE2()
  • int Sleef_cpuSupportsSSE4_1()
  • int Sleef_cpuSupportsAVX()
  • int Sleef_cpuSupportsFMA4()
  • int Sleef_cpuSupportsAVX2()
  • int Sleef_cpuSupportsAVX512F()
• AArch64
  • int Sleef_cpuSupportsSVE()
• AArch32
  • int Sleef_cpuSupportsNEON()
  • int Sleef_cpuSupportsNEON_VFPV4()
• POWER
  • int Sleef_cpuSupportsVSX()