You need to add the library dependencies, not the library itself.
Looking at other examples, i instead tried adding:
libgwm_la_LIBADD = `gwm_link`
But this still results in the same error as above.
I've just pushed a patch which should fix it since libgwm now knows what it depends on:
/star/lib/libgwm.dylib:/star/lib/libgwm.0.dylib (compatibility version 1.0.0, current version 1.0.0)/opt/X11/lib/libSM.6.dylib (compatibility version 7.0.0, current version 7.1.0)/opt/X11/lib/libICE.6.dylib (compatibility version 10.0.0, current version 10.0.0)/opt/X11/lib/libX11.6.dylib (compatibility version 10.0.0, current version 10.0.0)/opt/X11/lib/libXt.6.dylib (compatibility version 7.0.0, current version 7.0.0)/star/lib/libemsf.0.dylib (compatibility version 1.0.0, current version 1.0.0)/star/lib/libems.0.dylib (compatibility version 1.0.0, current version 1.0.0)/star/lib/libcnf.0.dylib (compatibility version 1.0.0, current version 1.0.0)/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1197.1.1)/star/lib/libstarmem.0.dylib (compatibility version 1.0.0, current version 1.0.0)
Maybe that will fix it for you.
I have no real idea why people are coming across this problem now.