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>

Introduced in C++17. It replaces gcc's warn_unused_result.

Found with modernize-use-nodiscard.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

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.

Rename struct Encoder to PreparedEncoder, and add a new (abstract)
class Encoder which represents one encoder instance.

The old struct config_param remains only for top-level string options.

.. and move the plugins to src/encoder/plugins/.

The MPD core will add this as a prefeix.

Replaces GLib's GError.

Don't deinterleave manually, don't allocate memory.

When you don't explicitly set an output sample rate, liblame tries to
guess an output sample rate from the input sample rate.  You would
think that this "guessing" consists of just setting both equal, but
that is not the case.  For 44.1kHz at 96kbit/s, liblame chooses
32kHz.  This patch explicitly configures the output sample rate, to
stop the bad guessing.