[console] Do not share ANSI escape context between lineconsole users
An ANSI escape sequence context cannot be shared between multiple
users. Make the ANSI escape sequence context part of the line console
definition and provide individual contexts for each user.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
[syslog] Separate out generic line-based console functionality
Abstract out the generic line-handling portions of the syslog
putchar() routine, to allow use by other console types.
Signed-off-by: Michael Brown <mcb30@ipxe.org>