DirectSound: use calloc for aout_stream_sys_t

Fix a crash occurring when CreateDSBufferPCM() fails in Start() and
afterwards Stop() uses uninitialized pointer values when releasing
objects.

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
DirectSound: avoid double call to release function

If Start() failed, IDirectSound_Release() was called twice.

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net> with changes
Revert "auhal: rework channel mapping for analog surround output"

This reverts commit c3bb23cd68f36ea37cf8d6ecb7cc187cd47c1c38.
Revert "auhal: fix wrong analog 5.1 channel ordering (close #8589)"

This is superseded by a proper fix.
This reverts commit fa396d194fa58097223475d8038605f10a5041c5.
auhal: simplify switch by mapping with an array
auhal: correctly fix channel ordering by setting the correct scope.

fixes #10125, #10199
auhal: rename layout variable to make more clear that this is the input layout