unix: squelch compiler warning on release builds
unix: squelch compiler warning on release builds

Fixes: https://github.com/libuv/libuv/issues/343

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso