egl: Don't use SDL_LoadFunction to get GL entry points on Emscripten.

This results in a dlsym() call, which causes Emscripten to panic if the game
wasn't explicitly built dlopen support. eglGetProcAddress works just fine on
this platform, so just let that codepath handle it.

--HG--
extra : rebase_source : 7cf75ced6741da7762b0bbe8e86c8ab4c70dcbd3
1 file changed