As a preliminary step for working on issue #11, this patch revisits the
'Framebuffer::info' RPC call. Instead of using C-style out paramters,
the new 'mode()' RPC call returns the mode information as an object of
type 'Mode'. Consequently, mode-specific functions such as
'bytes_per_pixel' have been moved to the new 'Framebuffer::Mode' class.
At the startup of python's termios module, a sequence of 'tcgetattr' and
'tcsetattr' calls is executed. If one of those calls fails, the
initialization gets canceled. 'tcgetattr' is implemented via ioctl
operations on stdout. To let those operations succeed, the default
implementation of ioctl ('Plugin::ioctl') cannot be used because it
returns -1. Adding a dummy ioctl to the libc_log back end alleviates
this problem.
Removed dummy implementation of '_ioctl'. This function is called
internally within the libc, i.e., by 'tcgetattr'. For running
libreadline in Noux, we need to hook into those ioctl operations via
the libc plugin interface.
