[HarfBuzz] harfbuzz: Changes to 'rvalue-reference'

[Behdad Esfahbod]

New branch 'rvalue-reference' available with the following commits:
commit 40531065c3041c5e65e0197b8e140585a8ff051d
Author: Behdad Esfahbod <behdad at behdad.org>
Date:   Tue Aug 28 17:04:52 2018 -0700

    C++11 solution for previous commit
    
    Let's see which gods (new term we use to refer to build bots) we anger.
    Will revert after.