Originally these functions were exposed on all GLSL ES 300 devices. However, that causes a build error as Android devices expose the *Unorm4x8 functions despite them not being in the ES 300 spec
Add necessary build flags and switch from using a
GLES2 context to a GLES3 one.
This also enables building for OpenXR
Co-authored-by: m4gr3d <fhuyakou@gmail.com>
Co-authored-by: dsnopek <dsnopek@gmail.com>
