Add SurfaceFactoryQt and OzonePlatformEglfs.

SurfaceFactoryQt::loadEGLGLES2Bindings is needed to find
and load EGL and GLES2 libraries on embedded linux.
It also provides a function to query the native display.

We are using qmake variables at compile time to detect
where we should look for the libraries at runtime.

For EGLFS we query the native display through PlatformNativeInterface.
If the resource is not exposed by Qt (pre 5.4),
then we assume EGL_DEFAULT_DISPLAY, which is the right
parameter for close to 100% of the cases anyway.

OzonePlatformEglfs is just boiler plate code.

Change-Id: I3ad08a56c50d6160be653ffb168b3f1f791e5245
Reviewed-by: Andras Becsi <andras.becsi@digia.com>