Merge r1470186:

Fix PPC atomics to work with gcc 4.0

PR: 54840
Submitted by: Mattias Engdegård <mattiase acm org>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.4.x@1470192 13f79535-47bb-0310-9956-ffa450edef68