plugins vs. licensing

[Joern Rennecke]

Couldn't the plugin interface require a copyrighted passphrase to be
sent by the plugin when it registeres, and the passphrase can then
be licensed under the GPL.  Thus, plugins that want to interface with
an official FSF gcc will have to be GPLed in order to talk to the
plugin interface, and we don't need to tinker with the runtime licensing.