[oe] libatomic RPROVIDES

[Tim Godfrey]

Hello!

The packagegroup-qt5-toolchain-target recipe has a runtime dependency on
(among others):
 - libatomic
 - libatomic-dev
 - libatomic-staticdev

and I got an error (building the meta-toolchain-qt5 recipe) complaining
that nothing provides it. Meanwhile, the external-linaro-toolchain recipe
makes packages for each of those dependencies but doesn't list them in
PROVIDES or RPROVIDES.

Is there a reason they are not listed? Would it be more correct to list
those packages in PROVIDES or RPROVIDES?

Thanks!
Tim