Copy the more efficient HTTP header parser from QtNetwork
Copy the more efficient HTTP header parser from QtNetwork

The one from QtNetwork is more efficient, since it doesn't use regular
expressions. This also solves a use of uninitialised variables.

error: ‘httpStatusCode’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

Change-Id: Id7f203d971564651eb0bd63d3d54d074be947793
Reviewed-by: Kurt Pattyn <da83d6ada5df79ff647b4271d0d788c6f1bafca2@gmail.com>

pixty/qtwebsockets,remimixlr/QtWebsocket,pixty/qtwebsockets