In commit efe48189bf (cmake-gui: Restore application icon on macOS,
2020-10-13, v3.19.0-rc1~2^2) and commit f7ae4f572b (cmake-gui: Restore
application icon on Windows, 2020-10-13, v3.19.0-rc1~1^2) we attached
the icon source files to all consumers of `CMakeGUILib`, but that
includes other libraries like `CMakeGUIMainLib`. The latter library is
meant only for direct consumption by a GUI executable, so use that to
propagate the icons instead.
440ee739c4
