[binutils-gdb] Update NEWS post GDB 8.0 branch creation.

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 305d16a9beff2a817ee03b3881da68eb3a29edec ***

Author: Joel Brobecker <brobecker@adacore.com>
Branch: master
Commit: 305d16a9beff2a817ee03b3881da68eb3a29edec

Update NEWS post GDB 8.0 branch creation.

gdb/ChangeLog:

	* NEWS: Create a new section for the next release branch.
	Rename the section of the current branch, now that it has
	been cut.