Update .def files for 4.6 branch

Building Qt for symbian from the 4.6 branch (HEAD = 23f3c92081a8afd6ff4be352fee407817950e72f) fails with the following error:

MAKEDEF ERROR: 1 Frozen Export(s) missing from object files:
  \iwmake\buildS60____PADDING________\src\s60installs\bwins\QtGuiu.def(12600) : ?display@QEglContext@@QBEHXZ @12599    

Note that there may be dependencies on the 4.7.0 versions of the def files, e.g. new indexes already used in 4.7.0 cannot be allocatesd to different symbols in 4.6.3.