When using gcc 4.2, build the alsa plugin raises the following warning:

gstalsadeviceprobe.c:64: warning: the address of 'info' will always evaluate as 'true'

The reason is because that line is : 
snd_ctl_card_info_alloca (&info);

and snd_ctl_card_info_alloca is in fact a macro which would expand as follow (based on the above line):
  assert(&info);
  info = (snd_ctl_card_info_t *) alloca(snd_ctl_card_info_sizeof());
  memset(info, 0, snd_ctl_card_info_sizeof());

The problem is the assert(&info); since info was defined just above, it's guaranteed that the address  of 'info' will always evaluate as 'true'.

To fix that:
* either fix the alsa headers to have 'hassert (ptr != NULL);'
* Add -Wno-address to the CFLAGS