glsl: Add usual extension boilerplate for OES_shader_image_atomic.

v2: No need for extension enable bits (Ilia).

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>

src/compiler/glsl/glsl_parser_extras.h

@@ -593,6 +593,8 @@ struct _mesa_glsl_parse_state {
    bool OES_geometry_point_size_warn;
    bool OES_geometry_shader_enable;
    bool OES_geometry_shader_warn;
+   bool OES_shader_image_atomic_enable;
+   bool OES_shader_image_atomic_warn;
    bool OES_standard_derivatives_enable;
    bool OES_standard_derivatives_warn;
    bool OES_texture_3D_enable;