Fixes crash after database update.

Fixes initialization failure.

There is no advantage in using g_setenv().

The upper-case name seems to be the canonical one.

Allow library auto-detection without pkg-config.

Finally, MPD runs on Android.  For some small value of "runs".  Very
much work left, too much to describe.

Doesn't work yet, just to get the Android port started.

This is what we get from the storage plugin via FileInfo.  Fixes a
compiler warning on Mac OS X where dev_t appears to be signed.

Define "ANDROID" if the host operating system is Android.

Fixes build failure caused by commit d9466cad.

Fixes nullptr dereference (regression by commit df5f9f4a).