We need to have USE=static-libs because this package install '.a' files: /usr/games/lib64/crossfire/plugins/cfnewspaper.a /usr/games/lib64/crossfire/plugins/cfanim.a /usr/games/lib64/crossfire/plugins/citylife.a /usr/games/lib64/crossfire/plugins/cfpython.a /usr/games/lib64/crossfire/plugins/cflogger.a /usr/games/lib64/crossfire/plugins/cfanim.so /usr/games/lib64/crossfire/plugins/cfnewspaper.so /usr/games/lib64/crossfire/plugins/citylife.so /usr/games/lib64/crossfire/plugins/cfpython.so /usr/games/lib64/crossfire/plugins/cflogger.so /usr/games/lib64/crossfire/plugins/cfanim.la /usr/games/lib64/crossfire/plugins/cfpython.la /usr/games/lib64/crossfire/plugins/citylife.la /usr/games/lib64/crossfire/plugins/cflogger.la /usr/games/lib64/crossfire/plugins/cfnewspaper.la
There's no reason to have the .a files around at all so 1.71.0 just doesn't have them around anymore.