Issue #20966: Fix Tkinter Resources link
Closes #20966: Fix Tkinter Resources link (merge from 3.4)
Ignore files generated by MSVC PGO builds.
Ignore files generated by MSVC PGO builds (merge from 3.4).
Clean up PCbuild/pcbuild.sln a bit:

- Remove configuration settings from removed _sha3.vcxproj
- Don't try to build configurations of _testembed that don't exist
  (namely, PGInstrument and PGUpdate)
Merge PCbuild/pcbuild.sln cleanup from 3.4
Avoid compile warning in xxlimited on 32-bit Windows non-Debug builds.
Merge xxlimited compile warning fix from 3.4