[Alsaplayer-devel] configure system

[Dominique Michel]

A few things seam to be wrong configure.ac (from the worst to the less worst):

- make try to compile the mad plugin even when libmad is not found;
- gtk1 is still tested;
- oggflac is tested with recent libflac. As it is included in libflac with the
new API, it is enough to only test libflac for both libflac and oggflac;
- nls is working now, so I guess that

if test "$enable_nls" = yes; then
echo No nls support yet
fi

is not needed anymore.
The funny part is that I don't get this echo during configure when nls was to
yes...

I will try to look at it and report back.

Dominique