MFH: r475871

lang/erlang-runtime{20,21}: Add patch to fix build on i386

Those two ports fail to build on FreeBSD/i386 (all versions) for quite
some time. The Erlang/OTP team provided a patch after Dewayne Geraghty
reported the issue upstream.

Here is the entry in the Erlang/OTP bug tracker:
https://bugs.erlang.org/browse/ERL-677

The patch was successfully tested on FreeBSD 10.4 and 11.1, both i386
and amd64. Dewayne also confirmed success on FreeBSD 11.2.

PR: 229600
Reported by: Dewayne Geraghty <dewayne@heuristicsystems.com.au>
Obtained from: https://bugs.erlang.org/browse/ERL-677

Approved by: portmgr (riggs)