sys-devel/binutils: fix *.mo file collision in live ebuild, bug #641036

sys-devel/binutils: fix *.mo file collision in live ebuild, bug #641036

Upstream commit ca39c2f4dd0fedcaaee348be7a913f0c14876796
(https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=ca39c2f4dd0fedcaaee348be7a913f0c14876796)
added support for overriding datarootdir without need for sed hack we had.

It broke our hack but we can remove it completely and use
--datarootdir= instead.

Thanks to Manuel Lauss!

Fixed-by: Manuel Lauss
Closes: https://bugs.gentoo.org/641036
Package-Manager: Portage-2.3.19, Repoman-2.3.6