Revert "got rid of "given { when {} }" because it emits a warning too and workaround is more ugly than a couple of "if"s"

This reverts commit ac51491b7c26d935b64c1a3690759c287b698b90.
Revert "got rid of the "~~" operator because it's considered experimental and emits a warning on newer versions of Perl"

This reverts commit cf411c90226fb8ddbf99cf5d1847a08b4fb6e1c0.
shut the warnings up in MediaWords::CommonLibs instead