Register new snapshots
std: Rename {Eq,Ord} to Partial{Eq,Ord}

This is part of the ongoing renaming of the equality traits. See #12517 for more
details. All code using Eq/Ord will temporarily need to move to Partial{Eq,Ord}
or the Total{Eq,Ord} traits. The Total traits will soon be renamed to {Eq,Ord}.

cc #12517

[breaking-change]
syntax: Prepare for Total{Eq,Ord} => {Eq,Ord}

This commit adds the groundwork for the renaming of the Total{Eq,Ord} traits.
After this commit hits a snapshot, the traits can be renamed.
auto merge of #14534 : alexcrichton/rust/snapshots, r=sfackler

This is part 2 of the saga of renaming the Partial/Total equality and comparison traits.