Add support for FreeBSD closefrom

Add closefrom support for FreeBSD.

Implemented in OTP 17:
https://github.com/erlang/otp/blob/OTP-17.0/erts/configure.in#L1166
https://github.com/erlang/otp/blob/OTP-17.0/erts/emulator/sys/unix/erl_child_setup.c#L114-L119

and WhatsApp's R16b01:
https://github.com/reedr/otp/commit/b3420b3632c94d4c4869e88f057ca659aa513aea