erts: Fix erlexec to not append -- to args if no env flags are set
erts: Fix erlexec to not append -- to args if no env flags are set

Not having this broke: `erl -man erl`

lrascao/otp,rlipscombe/otp,mikpe/otp,uabboli/otp,g-andrade/otp,lrascao/otp,potatosalad/otp,erlang/otp,lrascao/otp,dumbbell/otp,bjorng/otp,dgud/otp,getong/otp,vinoski/otp,dgud/otp,dgud/otp,isvilen/otp,isvilen/otp,electricimp/otp,potatosalad/otp,kvakvs/otp,emacsmirror/erlang,rlipscombe/otp,vladdu/otp,electricimp/otp,g-andrade/otp,rlipscombe/otp,jj1bdx/otp,lrascao/otp,jj1bdx/otp,erlang/otp,emacsmirror/erlang,lrascao/otp,uabboli/otp,jj1bdx/otp,kvakvs/otp,rlipscombe/otp,electricimp/otp,electricimp/otp,vinoski/otp,vladdu/otp,electricimp/otp,dgud/otp,dgud/otp,uabboli/otp,dgud/otp,vladdu/otp,getong/otp,erlang/otp,rlipscombe/otp,potatosalad/otp,rlipscombe/otp,dumbbell/otp,vladdu/otp,mikpe/otp,jj1bdx/otp,bjorng/otp,emacsmirror/erlang,mikpe/otp,mikpe/otp,mikpe/otp,isvilen/otp,mikpe/otp,dumbbell/otp,kvakvs/otp,jj1bdx/otp,potatosalad/otp,emacsmirror/erlang,vinoski/otp,dgud/otp,vinoski/otp,g-andrade/otp,lrascao/otp,mikpe/otp,bjorng/otp,ferd/otp,getong/otp,g-andrade/otp,electricimp/otp,bjorng/otp,lrascao/otp,lrascao/otp,g-andrade/otp,uabboli/otp,bjorng/otp,ferd/otp,rlipscombe/otp,emacsmirror/erlang,ferd/otp,emacsmirror/erlang,kvakvs/otp,vinoski/otp,mikpe/otp,emacsmirror/erlang,uabboli/otp,dgud/otp,potatosalad/otp,jj1bdx/otp,potatosalad/otp,electricimp/otp,vinoski/otp,getong/otp,dumbbell/otp,potatosalad/otp,kvakvs/otp,isvilen/otp,vladdu/otp,getong/otp,getong/otp,getong/otp,erlang/otp,emacsmirror/erlang,isvilen/otp,g-andrade/otp,vladdu/otp,vladdu/otp,vinoski/otp,getong/otp,mikpe/otp,uabboli/otp,potatosalad/otp,isvilen/otp,isvilen/otp,jj1bdx/otp,isvilen/otp,ferd/otp,bjorng/otp,kvakvs/otp,uabboli/otp,bjorng/otp,rlipscombe/otp,uabboli/otp,electricimp/otp,dgud/otp,erlang/otp,jj1bdx/otp,vinoski/otp,potatosalad/otp,g-andrade/otp,emacsmirror/erlang,dumbbell/otp,dumbbell/otp,vinoski/otp,bjorng/otp,vladdu/otp,getong/otp,isvilen/otp,jj1bdx/otp,rlipscombe/otp,ferd/otp,g-andrade/otp,rlipscombe/otp,potatosalad/otp,dumbbell/otp,jj1bdx/otp,lrascao/otp,ferd/otp,mikpe/otp,bjorng/otp,erlang/otp,dgud/otp,dumbbell/otp,emacsmirror/erlang,erlang/otp,erlang/otp,kvakvs/otp,isvilen/otp,getong/otp,bjorng/otp,g-andrade/otp,ferd/otp,erlang/otp,g-andrade/otp,kvakvs/otp,uabboli/otp,dumbbell/otp,vladdu/otp,ferd/otp,electricimp/otp,vinoski/otp,kvakvs/otp,ferd/otp,erlang/otp,dumbbell/otp