Fix the following error when running autoreconf by moving ACLOCAL_AMFLAGS definition into Makefile.am:
configure.in:251: warning: macro `AM_PATH_XMMS' not found in library
autoreconf: running: /usr/bin/autoconf --force
configure.in:251: error: possibly undefined macro: AM_PATH_XMMS
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1