Move GCCBUGURL to version.c; add commentary

[Geert Bosch]

On Tuesday, Oct 8, 2002, at 02:26 America/New_York, Zack Weinberg wrote:
> Well, it _should_, but the reality is that comperr.adb intercepts
> internal_error() and prints out a different message - which is out of
> date (PR ada/5856 is related).  I am willing to attempt to fix this,
> but my fix will take the form of tearing out the entire "bug box,"
> leaving only the 'please include all of the source files listed below'
> message over and above the normal ICE message.

The problem with the normal ICE message is that it does not provide
helpful information about where exactly the error is coming from.
GNAT provides the exact location (including column) and also provides
information about which instantiation of a generic triggered the bug.
This additional information is very useful for users to work around
problems in the front end, or for developers to trim down a testcase.

   -Geert