The Android/Quest CMakeLists.txt patch previously reimplemented desktop

immediate-mode GL (glBegin/glVertex3f/glEnd and friends) from scratch on
top of GLES, since GLES has none of it. That code compiled but was never
actually exercised - no on-screen verification was possible without real
Quest hardware - making it the biggest unverified risk in the port.

Replace it with GL4ES (MIT-licensed, prebuilt into the build image),
a mature desktop-GL-on-GLES translation library used by other
Quest/Android game ports for exactly this problem. This cuts
04-android-opengl-es-render.patch by half, deleting the hand-written
vertex-accumulation emulation entirely; alpha test, point sprites, and
point size stay on their existing GLES-native fixes rather than trusting
GL4ES's shakier custom-shader interop for those.

Bump build-image/VERSION to 3 - a fresh image with GL4ES cross-compiled
for arm64-v8a was built and make apk verified successfully against it.

android/engine-patches/02-android-opengl-es.patch

@@ -1,17 +1,19 @@
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
-@@ -46,9 +46,15 @@
+@@ -46,9 +46,17 @@
 
  add_compile_options(-fsigned-char -fno-strict-aliasing)
 
 -# Find OpenGL
 +# Find OpenGL. Android has no desktop GL/GLX for CMake's FindOpenGL module
-+# to find - just link the NDK's own GLESv2/EGL libraries directly.
++# to find - link the prebuilt GL4ES instead (translates this file's
++# desktop-style GL calls into GLES/EGL; it links GLESv2/EGL itself, so
++# the engine doesn't need to link them directly).
  if(ENABLE_OPENGL)
 -	find_package(OpenGL REQUIRED)
 +	if(ANDROID)
-+		set(OPENGL_INCLUDE_DIRS "")
-+		set(OPENGL_LIBRARIES GLESv2 EGL)
++		set(OPENGL_INCLUDE_DIRS /opt/prebuilt/android/gl4es/include)
++		set(OPENGL_LIBRARIES /opt/prebuilt/android/gl4es/lib/libGL.so)
 +	else()
 +		find_package(OpenGL REQUIRED)
 +	endif()