Function gstreamer_gl_sys::gst_gl_shader_string_get_highest_precision

pub unsafe extern "C" fn gst_gl_shader_string_get_highest_precision(
    context: *mut GstGLContext, 
    version: GstGLSLVersion, 
    profile: GstGLSLProfile
) -> *const c_char

This is supported on crate feature v1_16 only.