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.

Fixes another crash bug caused by commit
64d141f7

Fixes crash bug caused by commit
64d141f7

Caused by commit 64d141f7

This wasn't a serious memory leak, because after a mount failure, MPD
would abort anyway, which is subject to the next commit.

This source file isn't compiled when the database is disabled.

Signed-off-by: FlashSystems <developer@flashsystems.de>