Expects: AX    0000H
Returns: CF    Carry Flag is clear (NC) is successful and...
ES:BX address of a SwVersionRec structure
Info: Use a FAR call to the switcher entry address (see INT 2fH 4b02H)
to obtain info about the active task switcher, including its
name, version number, and the APIs it supports.

See SwVersionRec for a layout of the returned data.

INT 2fH 4bxxH (switcher functions)
- -

SwSrvc Fn 0000H: Get Switcher Version