alsabat: fills /tmp until out of memory

[eurofun]

alsabat creates its capture file by using mkstemp() in bat.c. So it creates a new file under /tmp each time it runs (at least when
configured to capture something...) and never removes any until no space is left.
I propose it should by default delete the files it opened after analysis and keep the current behavior as an option in order
to allow inspecting captured files after alsabat ran. Or alternatively an option to specify the capture filename.