The 'bindist' enforcement for openssl in the ebuild for v0.4.2 of libp11 is neither necessary nor helpful and breaks all openssl based installs not using 'bindist', i.e. about any openssl based installation. Note that you cripple anything EC based out of openssl with this strange enforcement and btw cause binary incompatability which requires a complete rebuild of anything depending on openssl. Removing this enforcement which was seemingly made to hide deficiencies in libressl (see https://github.com/OpenSC/libp11/issues/135) from the ebuild allows for an error free and working emerge. Please do not break working installations by introducing artificial restrictions.
sorry, my bad, had a typo, missing = in bindist USE flag.