tg-info: omit annihilated dependencies from list
When showing the "Depends:" list for a branch omit any dependencies
that have been annihilated. This matches the behavior of other
TopGit commands and annihilated branches are supposed to just
"get out of your way".
However, if `--verbose` is given at least twice, then do include
them (just like `tg summary --verbose --verbose --list` does) with
an annotation that they've been annihilated.
A side-effect of this change is that `tg info` now handles oddly
formatted `.topdeps` files a bit more gracefully.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>