add -A option for checkdeps in merge-topic & checkout-topic

[kpedro88]

As discussed with @smuzaffar in #80, this option will allow further simplification of the patch release build commands:

scram p $BASE_REL
cd $BASE_REL/src/
cmsenv
git cms-checkout-topic -A $PATCH_REL
git cms-addpkg -y FWCore/Version

[cmsbuild]

A new Pull Request was created by @kpedro88 (Kevin Pedro) for branch master.

@cmsbuild, @smuzaffar, @mrodozov, @iahmad-khan, @davidlange6 can you please review it and eventually sign? Thanks. You can sign-off by replying to this message having '+1' in the first line of your reply. You can reject by replying to this message having '-1' in the first line of your reply.

external issue cms-sw/cmsdist#3045

[smuzaffar]

thanks @kpedro88.