--enable-plugin as default?

[Jack Howarth]

   I am wondering why we don't default on --enable-plugin
in gcc 4.6 (and perhaps 4.5.1) for those hosts that are
known to have working testsuite results of plugin.exp?
The additional overhead for building the plugin support is
close to nil and the user has to explicitly invoke the loading
of a compiler plugin (so that it shouldn't destabilize in
the default usage of the compiler).
               Jack