Log Message:
lang/erlang: Fix cross-build.

1. Perl is not actually needed at run-time -- it's a build-time tool
   dependency.

2. Erlang depends on a native build of itself to cross-build.

3. Need to pass through erl_xcomp_sysroot=/ to pacify configure.

Revbump because this ditches the run-time Perl dependency.
Otherwise, no change to native builds.