gcc.texi (Bug Lists): Do not mention newsgroups nor the possibility to report bugs...

gcc.texi (Bug Lists): Do not mention newsgroups nor the possibility to report bugs via postal mail.

	* gcc.texi (Bug Lists): Do not mention newsgroups nor the
	possibility to report bugs via postal mail. Change a URL and
	merge in a nearly duplicate statement...
	(Bug Reporting): ...from here.
	(Service): Refer to the Bug Reporting section instead of
	duplicating an URL.
	(Contributing): Remove trivial explanations concerning snapshots.

From-SVN: r39074