ArchitectureX86{-64}:
- Implement helper functions for adding floating point and SIMD registers.
- Add st0-st7 and mm0-mm7 to the list of exposed x86{-64} registers,
along with their DWARF unwind mappings.
- Add xmm0-xmm7 for x86, and xmm0-xmm15 for x86-64.
CpuStateX86{-64}:
- Implement helper functions for setting/retrieving floating point and SIMD
register values.
- Fill in values for st*, mm* and xmm* from debug_cpu_state.