mesa: FEATURE_dispatch to control dispatch table usage

src/mesa/main/context.c

@@ -1168,7 +1168,9 @@ _mesa_initialize_context(GLcontext *ctx,
       if (ctx->Exec)
          _mesa_free(ctx->Exec);
    }
+#if FEATURE_dispatch
    _mesa_init_exec_table(ctx->Exec);
+#endif
    ctx->CurrentDispatch = ctx->Exec;
 #if FEATURE_dlist
    _mesa_init_dlist_table(ctx->Save);

src/mesa/main/mfeatures.h

@@ -40,6 +40,7 @@
 #define FEATURE_attrib_stack  _HAVE_FULL_GL
 #define FEATURE_colortable  _HAVE_FULL_GL
 #define FEATURE_convolution  _HAVE_FULL_GL
+#define FEATURE_dispatch  _HAVE_FULL_GL
 #define FEATURE_dlist  _HAVE_FULL_GL
 #define FEATURE_draw_read_buffer  _HAVE_FULL_GL
 #define FEATURE_drawpix  _HAVE_FULL_GL