OK, scummvm got built against libSDL 1.2, and apparently one needs to disable OpenGL there explicitly. In theory it might use GLES, but scummvm doesn't work with libSDL 2.0 yet, and that's what is needed for using the GLES option.

I'll see how this works with Plasma Active (but that will have to wait until some bug fixes, since current devel image on Nexus 7 is in unusable condition and that's what I have now to test Mer builds on).