2 framework changes, virtio_console bugfixes and 2 new subtests

Hi guys,

sorry for long pull request, I just wanted to add 2 new subtests and I end up with lots of changes.

Summary:
* aexpect: add read_until_any_line_matches() function
* env_process: fix exit condition of background screendump thread
* ADD: incorrect_options.boot_too_much_ports subtest
* ADD: interrupted_transfer.suspend subtest
* FIX: lots of background thread handling on virtio_console test failure
* FIX: some sigio test problems

Now I'm able to execute all virtio_console tests test (136) and in the end there are only tail_threads and the process finishes successfully.

Tested on F17&F18_guest with custom qemu-1.3.91 + custom seabios (support for S3 is disabled in F17)