Should fix MSVC buildbots:

https://lab.llvm.org/buildbot/#/builders/197/builds/8321
https://lab.llvm.org/buildbot/#/builders/211/builds/1549

This is done for consistency with LiveRegUnits (see #154325). This is
technically not an NFC, as `MBB.liveouts()` excludes runtime-defined
liveins, but no users currently depend on this.

ISD::ADDC, ISD::ADDE, ISD::SUBC and ISD::SUBE are being deprecated,
using ISD::UADDO_CARRY,ISD::USUBO_CARRY instead. Lowering the UADDO,
UADDO_CARRY, USUBO, USUBO_CARRY in the patch.

Callee saved registers should always be phyiscal registers. They are
often passed directly to other functions that take MCRegister like
getMinimalPhysRegClass or TargetRegisterClass::contains.

Unfortunately, sometimes the MCRegister is compared to a Register which
gave an ambiguous comparison error when the MCRegister is on the LHS.
Adding a MCRegister==Register comparison operator created more ambiguous
comparison errors elsewhere. These cases were usually comparing against
a base or frame pointer register that is a physical register in a
Register. For those I added an explicit conversion of Register to
MCRegister to fix the error.

Update some other places to avoid implicit conversions this introduces,
but I probably missed some.

Differential Revision: https://reviews.llvm.org/D148613