`man gcc`, scroll to the bottom of the page, and: Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "GNU General Public License" and "Funding Free Software", the Front-Cover texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the gfdl(7) man page. `man gfdl` also brings "FDL-1.3 or any later version" up
It might be wrong even before 4.7.0, I didn't look.
(In reply to comment #0) as mentioned in a previous bug, we don't care. set LICENSE to whatever you want in any toolchain package.