Change QT_NO_WEBKIT to MARBLE_NO_WEBKIT
Review Request #124526 - Created July 29, 2015 and submitted
qt4/Qt/qconfig.h sets QT_NO_WEBKIT without checking whether it is installed or not. This screws up our logic later on. The patch moves from QT_NO_WEBKIT to MARBLE_NO_WEBKIT and tries to guess its value based on the cmake checks if not given from the command line.
The patch is for master, a backport for Applications/15.04 is at http://nienhueser.de/marble/marble-nowebkit-1508-1.diff
Compiling Applications/15.04 branch with Qt 4.8 + QtWebKit installed, and master with Qt 5.5 Desktop and Qt 5.5 Android