This series adds support for a number of more or less recently announced
ISA extensions. The series interacts mildly (and only contextually) with
the AVX512-FP16 one. Note that an intended final patch (to fit in USER_MSR
elsewhere, in particular in VMX code) is yet to be written; specifically
I haven't checked yet whether - like was the case for MSRLIST - there's
again insufficient detail in the specification.

1: x86emul: support LKGS
2: x86emul: support CMPccXADD
3: VMX: tertiary execution control infrastructure
4: x86emul+VMX: support {RD,WR}MSRLIST
5: x86: introduce x86_seg_sys
6: x86emul: support USER_MSR instructions

Jan