Support multiple master fds in the terminal emulator.
Support multiple master fds in the terminal emulator.

Notably, sshd does this, and we need to be sure to grab all of them.

developerfm/reptyr,nelhage/reptyr,yatsek/reptyr,nelhage/reptyr,yatsek/reptyr,developerfm/reptyr,nelhage/reptyr,developerfm/reptyr,yatsek/reptyr