contribs: mpg123 silently requires libltdl-dev

This fails regardless of the target platform. making it an immediate licence compliance problem.

autoreconf: running: aclocal --force -I m4
autoreconf: configure.ac: tracing
autoreconf: running: libtoolize --copy --force
libtoolize: putting auxiliary files in AC_CONFIG_AUX_DIR, 'build'.
libtoolize: copying file 'build/ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIRS, 'm4'.
libtoolize: copying file 'm4/libtool.m4'
libtoolize: copying file 'm4/ltoptions.m4'
libtoolize: copying file 'm4/ltsugar.m4'
libtoolize: copying file 'm4/ltversion.m4'
libtoolize: copying file 'm4/lt~obsolete.m4'
autoreconf: configure.ac: not using Intltool
autoreconf: configure.ac: not using Gtkdoc
autoreconf: running: aclocal --force -I m4
autoreconf: running: /usr/bin/autoconf --force
configure.ac:107: warning: The macro `AC_PROG_CC_C99' is obsolete.
configure.ac:107: You should run autoupdate.
./lib/autoconf/c.m4:1659: AC_PROG_CC_C99 is expanded from...
configure.ac:107: the top level
configure.ac:276: error: possibly undefined macro: LT_SYS_MODULE_EXT
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
autoreconf: error: /usr/bin/autoconf failed with exit status: 1
make: *** [../src/mpg123/rules.mak:43 : .mpg123] Erreur 1

This may be a forward incompatibility with libtool.