SUMMARY

On platform without X11, find_package(EGL) fails as it tries to compile code without EGL_NO_X11 define. This was encountered on SailfishOS where we have the following pkg-config EGL file:

```
[root@fdebf063bc5a builder]# cat /usr/lib/pkgconfig/egl.pc
prefix=/usr
libdir=${prefix}/lib
includedir=${prefix}/include

Name: egl
Description: Mesa EGL Library
Version: 21.1.6
Requires.private: libdrm >=  2.4.75
Libs: -L${libdir} -lEGL
Libs.private: -lpthread -pthread -lm -ldl
Cflags: -I${includedir} -DEGL_NO_X11
```

As -DEGL_NO_X11 was not used while checking for code compilation, HAVE_EGL was set to false. 

I am not an expert in CMake, but it looks like that define option should be somewhere here: https://invent.kde.org/frameworks/extra-cmake-modules/-/blob/master/find-modules/FindEGL.cmake#L100


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: SailfishOS 4.5
(available in About System)
KDE Plasma Version: -
KDE Frameworks Version: 5.105.0 
Qt Version: 5.15.8