Found with -Wunreachable-code-break
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former was deprecated with C++14.

According to the C++11 and C++17 standards, both files are identical.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Combining these two in one single value saves some memory, but is
complicated and we may need the src_sample_format for new features
later.

These options are exclusive.

Preparing to add more state.

The dop_buffer will be moved out soon.

Since we switched from autotools to Meson in commit
94592c14, we don't need to include
`config.h` early to properly enable large file support.  Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.

This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Move this sample rate fixup from the ALSA output plugin to PcmExport,
where it belongs.

DSD_U32 packs four bytes instead of one large "sample", thus the
sample rate is one quarter of the input sample rate.  This fixes a
rather critical DSD_U32 playback problem.

Prepare for DSD sample rate fixups.