Fixed bug 4684 - GLES1 variables missing under Android with CMake
Braden Obrzut
https://hg.libsdl.org/SDL/file/7dc39b047055/CMakeLists.txt#l911
I believe the following should also be specified there:
set(SDL_VIDEO_OPENGL_ES 1)
set(SDL_VIDEO_RENDER_OGL_ES 1)
As it is now GLES1 support is missing when building for Android despite it linking to the library.