ssh command on OS-X issues Linux IOCTL for TCSETPGRP

[slippycheeze]

The failure is illustrated here:

Errno::ENOTTY: Inappropriate ioctl for device - 
/Users/daniel/.rvm/gems/ruby-1.9.3-p194@rvc/gems/rvc-1.7.0/lib/rvc/util.rb:135:in `ioctl'
/Users/daniel/.rvm/gems/ruby-1.9.3-p194@rvc/gems/rvc-1.7.0/lib/rvc/util.rb:135:in `tcsetpgrp'
/Users/daniel/.rvm/gems/ruby-1.9.3-p194@rvc/gems/rvc-1.7.0/lib/rvc/util.rb:147:in `system_fg'
/Users/daniel/.rvm/gems/ruby-1.9.3-p194@rvc/gems/rvc-1.7.0/lib/rvc/modules/vm.rb:397:in `ssh'

It would be better to either catch that, or to detect the host platform and issue the platform specific IOCTL code instead.