If someone tries to use libmms and they do not have glib installed, it will fail because of:
# pkg-config --libs libmms
Package glib-2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `glib-2.0.pc'
to the PKG_CONFIG_PATH environment variable
Package 'glib-2.0', required by 'libmms', not found
Removing the Requires: glib... line from the files solves it.