[rfc] Print solib events in mi-mode

[Kris Warkentin]

Someone just pointed something out to me.  "set stop-on-solib-events 1" is
NOT enable-load-catchpoint or anything else.  Yes, those things should exist
for all solib platforms but the bottom line is that stop-on-solib-events is
not currently mi-enabled and it should be.

I want to make that command result in proper mi output, regardless of any
other things which might be implemented in the future.

cheers,

Kris