qmake5: set OE_QMAKE_INCDIR_QT

This is set when generation an SDK, and thus would be usefull to have also
when bitbaking. That allows us to use this in *.prf files which is used
both when bitbaking as well as when using the SDK.

Signed-off-by: Anders Darander <anders@chargestorm.se>
(cherry picked from commit 96e8d29fdbdf6fa656c854d9b55c5b0c213166a7)
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
qt5-git: Update to rc1+, latest revision in 5.4 branch

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>