sink-input, source-output: Interpret missing PCM parameters in format info as a request to decide those parameters at the server end
The "fix flags" (PA_SINK_INPUT_FIX_FORMAT etc.) don't work properly
with the pa_stream_new_extended() interface. This patch fixes it so
that the same effect can be achieved by leaving some of the PCM
parameters unspecified in format info objects. Also, when converting
a sample spec to a format info when using the old pa_stream_new()
interface, the "fix flags" are taken into account in that conversion.
BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=68952