It avoids a potential segfault after a silent avcodec audio API breakage.

It fixes at least WMAP decoding.

Minor changes by jb@videolan.org

This reverts commit a0f3831c.

DBus is synchronous

(We seldom have non ASCII characters here, but better safe than sorry)

Currently, only the core supports this correctly, however.

Note that this means key configuration values become case sensitive
(case insentivity would be too complicated), but this should not be
a problem so long as the core key<->string functions are always used.