Tag the 10.0.0 version bump.
The tag name, llvmorg-10-init, signifies that this is the initial commit
with major version number 10.
With this tag in place, git-describe can be used to generate nicer
names for commits on master, for example:
$ git describe
llvmorg-10-init--g
where is the number of commits since this tag.
The plan is to add this kind of tag together with future version bumps.
