compiler: move glsl_interface_packing enum to shader_enums.h

This allows us to drop the duplicate gl_uniform_block_packing enum.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/compiler/shader_enums.h

@@ -567,6 +567,13 @@ enum glsl_interp_mode
    INTERP_MODE_COUNT /**< Number of interpolation qualifiers */
 };
 
+enum glsl_interface_packing {
+   GLSL_INTERFACE_PACKING_STD140,
+   GLSL_INTERFACE_PACKING_SHARED,
+   GLSL_INTERFACE_PACKING_PACKED,
+   GLSL_INTERFACE_PACKING_STD430
+};
+
 const char *glsl_interp_mode_name(enum glsl_interp_mode qual);
 
 /**