Find first files from source forms
Find first files from source forms

Some projects use parse transforms but do not put them in
erl_first_files. We need to parse the files directly and
find the compile directives ourselves.

KrzysiekJ/erlang.mk,yannayl/erlang.mk,bsmr-erlang/erlang.mk,crownedgrouse/erlang.mk,michaelnisi/erlang.mk,ninenines/erlang.mk,ingwinlu/erlang.mk,hairyhum/erlang.mk,efcasado/erlang.mk,a12n/erlang.mk,nevar/erlang.mk,rabbitmq/erlang.mk,jj1bdx/erlang.mk