Attempt to inject eqc path to rebar3 erlang code compiler

[jadeallenx]

Lately we've been having compile failures like this

===> Compiling _build/test/lib/blockchain/eqc/path_v2_eqc.erl failed
_build/test/lib/blockchain/eqc/path_v2_eqc.erl:3: can't find include lib "eqc/include/eqc.hrl"; Make sure eqc is in your app file's 'applications' list
_build/test/lib/blockchain/eqc/path_v2_eqc.erl:9: undefined macro 'FORALL/3'
_build/test/lib/blockchain/eqc/path_v2_eqc.erl:82: undefined macro 'SUCHTHAT/3'

So this branch attempts to inject the eqc paths for the rebar3_erlc_compiler module, but... it still doesn't work. I'm opening this PR in the off chance that someone has an idea how to fix this problem.

[jadeallenx]

@tsloughter @Licenser @ThomasArts Please help? Any ideas or theories why this doesn't work?