Fix parsing of long latin strings in the json parser

Latin1 strings are usually stored as 8 bit data in the json binary
format. But that data structure has a size limitation of 16bit, so
we need to fall back to storing the string as 16 bit data if it is
too long.

Task-number: QTBUG-30946
Change-Id: I0069b1367030b0b2f819fd1f04e34c9e2534a2a3
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Fixes: QtNetwork compilation for OpenSSL < 1.0.0

Incorporate some more of the API changes between OpenSSL versions
0.9.8 and 1.0.0.

Task-number: QTBUG-31140

Change-Id: Ie719b34e3ec8751f0fbc07d315e82816c110762c
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>