qemu-io: Improve portability (win32 now supported).

* Add missing include for struct timeval.
* Replace non-portable strsep by local qemu_strsep.
* Use POSIX basename by including libgen.h.

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>