Build on debian

[smdaa]

On a debian system i get a Could NOT find MPG123 (missing: MPG123_INCLUDE_DIR) even after installing libmpg123-dev.

here is the output of dpkg-query -L libmpg123-dev

/.
/usr
/usr/include
/usr/include/x86_64-linux-gnu
/usr/include/x86_64-linux-gnu/fmt123.h
/usr/include/x86_64-linux-gnu/mpg123.h
/usr/include/x86_64-linux-gnu/out123.h
/usr/include/x86_64-linux-gnu/syn123.h
/usr/lib
/usr/lib/x86_64-linux-gnu
/usr/lib/x86_64-linux-gnu/pkgconfig
/usr/lib/x86_64-linux-gnu/pkgconfig/libmpg123.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/libout123.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/libsyn123.pc
/usr/share
/usr/share/doc
/usr/share/doc/libmpg123-dev
/usr/share/doc/libmpg123-dev/changelog.Debian.gz
/usr/share/doc/libmpg123-dev/changelog.gz
/usr/share/doc/libmpg123-dev/copyright
/usr/share/doc/libmpg123-dev/examples
/usr/share/doc/libmpg123-dev/examples/Makefile
/usr/share/doc/libmpg123-dev/examples/dump_seekindex.c
/usr/share/doc/libmpg123-dev/examples/extract_frames.c
/usr/share/doc/libmpg123-dev/examples/feedseek.c
/usr/share/doc/libmpg123-dev/examples/id3dump.c
/usr/share/doc/libmpg123-dev/examples/mpg123_to_out123.c
/usr/share/doc/libmpg123-dev/examples/mpglib.c
/usr/share/doc/libmpg123-dev/examples/scan.c
/usr/lib/x86_64-linux-gnu/libmpg123.so
/usr/lib/x86_64-linux-gnu/libout123.so
/usr/lib/x86_64-linux-gnu/libsyn123.so