The compile-time calculation for `factor` overflows because `1<<31`
cannot be represented by `int`.  By casting to `uintmax_t` first, we
can avoid this overflow.

Closes #380

This assertion currently fails for S32 due to integer overflow (#380).

This emits the event even if PlayerControl::Play() is used to replay
the current song, which emits the missing "player" idle event.

Closes #381

Replaces the workaround from commit
751fff07 which fixed only one of many
crash locations.

See:

 https://github.com/MusicPlayerDaemon/MPD/issues/373
 https://github.com/android-ndk/ndk/issues/831
 https://bugs.llvm.org/show_bug.cgi?id=32611

Closes #373

The flag `-stdlib=libc++` doesn't appear to work because it attempts
to load `libc++` and not `libc++_static`, and it omits `libc++abi`.

Closes #360

Closes #366

In this new order, a filter 'AlbumArtist ""' matches only on songs
which neither have `AlbumArtist` nor `Artist`.

Grouping in the "list" command was completely broken from the start,
unlike "count group".  I have no idea what I have been thinking when I
wrote commit ae178c77, but it didn't
make any sense.

This commit is a rewrite of the feature.

For clients to be able to detect this feature, this commit also
increments the protocol version.

Be consistent with "list" responses.

Just like AlbumArtist falls back to Artist, AlbumArtistSort should
fall back tom AlbumArtist, ArtistSort and finally Artist.

Closes #355

This improves the workaround from commit
b5ba94f1 and actually gives a useful
result for "list" with a disabled tag.

- Updated to upstream version 0.20.21.

release v0.20.21

Sometimes, the JVM returns a non-nullptr value with an exception
pending (seen on Android 1.6, maybe a Dalvik bug?).  Let's catch all
such cases.

MPD has minSdkVersion=21 which is above all the checks here.

Since nfs_stat_async is deprecated.