i965: Initialize intel_context::vtbl after calling intelInitContext()

intel_context::gen field is set by intelInitContext(). So, by calling
intelInitContext() before initializing the vtable, we can can construct
different vtables for different gens.

Specifically, this allows us to set the HiZ operations to be no-ops for
contexts for which HiZ is not enabled.

Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Chad Versace <chad@chad-versace.us>

src/mesa/drivers/dri/i965/brw_context.c

@@ -71,7 +71,6 @@ brwCreateContext(int api,
       return false;
    }
 
-   brwInitVtbl( brw );
    brwInitDriverFunctions( &functions );
 
    if (!intelInitContext( intel, api, mesaVis, driContextPriv,
@@ -81,6 +80,8 @@ brwCreateContext(int api,
       return false;
    }
 
+   brwInitVtbl( brw );
+
    /* Initialize swrast, tnl driver tables: */
    intelInitSpanFuncs(ctx);