mesa: Remove remaining FEATURE_ARB_vertex_buffer_object guards.

Since commit 82b9661894 and
34eae1c72a vbo support
is mandatory for all drivers. So, remove the remaining
FEATURE_ARB_vertex_buffer_object guards.

Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>

src/mesa/main/context.c

@@ -1133,9 +1133,7 @@ _mesa_free_context_data( struct gl_context *ctx )
    _mesa_reference_buffer_object(ctx, &ctx->DefaultPacking.BufferObj, NULL);
 #endif
 
-#if FEATURE_ARB_vertex_buffer_object
    _mesa_reference_buffer_object(ctx, &ctx->Array.ArrayBufferObj, NULL);
-#endif
 
    /* free dispatch tables */
    free(ctx->Exec);