x86emul: restore ordering within main switch statement

x86emul: restore ordering within main switch statement

Incremental additions and/or mistakes have lead to some code blocks
sitting in "unexpected" places. Re-sort the case blocks (opcode space;
major opcode; 66/F3/F2 prefix; legacy/VEX/EVEX encoding).

As an exception the opcode space 0x0f EVEX-encoded VPEXTRW is left at
its current place, to keep it close to the "pextr" label.

Pure code movement.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citirx.com>