libstdc++-7-pic-arm64-cross 7.3.0-28ubuntu1cross1 (amd64 binary) in ubuntu cosmic

 This is used to develop subsets of the libstdc++ shared libraries for
 use on custom installation floppies and in embedded systems.
 .
 Unless you are making one of those, you will not need this package.
 .
 This package contains files for arm64 architecture, for use in cross-compile
 environment.