PacketLineIn: Reuse internal lineBuffer for small strings
Most "ACK %s continue", "ACK %s common", "NAK" strings that are read
by the readACK() method and readString() are shorter than the
lineBuffer already available. Reuse that buffer when reading from
the network stream and converting to a string with RawParseUtils to
avoid unnecessary temporary byte array allocations.
Change-Id: Ibc778d9f7721943a065041d80fc427ea50d90fff Signed-off-by: Shawn O. Pearce <spearce@spearce.org>