Return SQUASH_PROCESSING if output buffer is full
Return SQUASH_PROCESSING if output buffer is full

If the first call to heatshrink_encoder_poll fills the output buffer, the
second call fails.

quixdb/squash,jibsen/squash,quixdb/squash,quixdb/squash,Cloudef/squash,jibsen/squash,jibsen/squash,Cloudef/squash,Cloudef/squash