If you happen to fetch a zip archive of the git repo and try to build
from that, you may, for example, ask erlc to build src/._rebar.erl.
._* are OS X resource forks and not real .erl files. This may also
happen with network filesystems on OS X. To fix that, limit the
files compiled by rebar to include only those which start with
a letter or a digit.

The combination of changes to rebar_erlc_compiler, and the fact
that erl_first_files is inherited, caused a regression. To fix
that, ensure every project uses its own .rebar/erlcinfo. While at
it, fix the issue that erl_first_files entries were not included
when initializing the dep digraph.

Reported-by: Louis-Philippe Gauthier
Reported-by: Roland Karlsson

Thanks: Tuncer Ayaz