aplay/arecord: handle parsing errors of parameter values
when a user enters a command, he expects his command to be executed
as specified or aborted if it is impossible to fulfill his request
right now a command like "arecord -d hw:1,0 --max-file-time 1h recording.wav"
will happily record something and exit without error status while the resulting
recording contains definitely not what the user requested
to fix this, the patch handles the number parsing function's error channel
and checks whether the parsed number has any trailing characters