Without -avoid-version, libtool creates a libwebrtc-util.so.0 and
libwebrtc-util.so.0.0.0 which are not cleaned up by make uninstall,
which in turn causes make distcheck to fail.
libwebrtc_util_la_SOURCES = modules/echo-cancel/webrtc.cc
libwebrtc_util_la_CXXFLAGS = $(AM_CXXFLAGS) $(SERVER_CFLAGS) $(WEBRTC_CFLAGS) -DHAVE_WEBRTC=1
libwebrtc_util_la_LIBADD = $(WEBRTC_LIBS)
+libwebrtc_util_la_LDFLAGS = -avoid-version
module_echo_cancel_la_CFLAGS += -DHAVE_WEBRTC=1
module_echo_cancel_la_LIBADD += libwebrtc-util.la