Store lock from SCM on Dep (#7087)
Store lock from SCM on Dep (#7087)

Hex's SCM.checkout returns package build tools in the lock, store this
information on the Dep struct so that the loader can pass this
information to SCM.managers/1.

Fixes hexpm/hex#468.
ggcampinho/elixir,michalmuskala/elixir,joshprice/elixir,pedrosnk/elixir,pedrosnk/elixir,lexmag/elixir,kimshrier/elixir,ggcampinho/elixir,kelvinst/elixir,lexmag/elixir,gfvcastro/elixir,elixir-lang/elixir,kelvinst/elixir,kimshrier/elixir,gfvcastro/elixir