mesa/cs: Add DispatchCompute() to driver function table.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/main/dd.h

@@ -1005,6 +1005,13 @@ struct dd_function_table {
 
    void (*MemoryBarrier)(struct gl_context *ctx, GLbitfield barriers);
    /** @} */
+
+   /**
+    * \name GL_ARB_compute_shader interface
+    */
+   /*@{*/
+   void (*DispatchCompute)(struct gl_context *ctx, const GLuint *num_groups);
+   /*@}*/
 };