www/iridium: copy snappy fix from chromium

just like chromium (from which it was forked), iridium embeds a copy
of snappy (the compression library) and cannot be fully switched to
the system-provided archivers/snappy in an easy way. consider this a
band-aid patch

Reported by: pkubaj
MFH: 2020Q1 (blanket: web browser, build fix)