params_free functions don't work

[GitHub issues - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-lib issue #341 was opened from imyxh:

The following code segfaults on the call to `snd_pcm_hw_params_free` on my machine:

```c
#include <alsa/asoundlib.h>
void main() {
	snd_pcm_hw_params_t *params;
	snd_pcm_hw_params_alloca(&params);
	snd_pcm_hw_params_free(params);
}
```

The same goes for `s/hw/sw/g`. Am I doing something wrong? In more complex examples it seems to fail with munmap_chunk complaining about an invalid pointer, or free complaining about an invalid size.

How are the `*_params_free` functions meant to be used?

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/341
Repository URL: https://github.com/alsa-project/alsa-lib