make local/remote need the COMMIT-SHA macro

[andreubotella]

The local and remote targets of the Makefile template define the SNAPSHOT-LINK text macro, which used to define the "snapshot as of this commit" link in the spec metadata. speced/bikeshed#1635, however, removed any usage of that macro, instead using a new COMMIT-SHA macro for the LS status, which those Makefile targets don't define.

This would be solved by removing the SNAPSHOT-LINK definition and adding one for COMMIT-SHA defining it to be the empty string, for example. However, this would create a link pointing to ./commit-snapshots//, which isn't ideal.

[annevk]

A bogus link is the plan in #7. I think that's fine personally. We don't support a full local deploy after all.