Makefile: GIT_DESCRIPTION: Also pay attention to lightweight tags
Makefile: GIT_DESCRIPTION: Also pay attention to lightweight tags

By default, `git describe` only considers annotated tags.  The `--tags`
flag makes it also consider lightweight tags.  Flynn consistently uses
annotated tags; everyone else (me, Shubham, Bjorn) not so much.

datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador