QCborStreamReader: use QByteArray directly if possible

QIODevice represents considreable overhead, even with just QBuffer, for
parsing simple things. Benchmarking showed it was spending 25% of the
parsing time inside one QIODevice function or another. So this commit
accomplishes two things:

1) it increases the buffer size from 9 bytes to up to 256, which should
   reduce the number of calls into the QIODevice
2) if the source data is a QByteArray, then use it directly and bypass
   the QIODevice, thus increasing performance considerably

Change-Id: I56b444f9d6274221a3b7fffd150c531c9d28e54b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

0 files changed, 0 insertions, 0 deletions