MOFED apparently has a /usr/include/infiniband/verbs.h that also
defines a (slightly different but fully compatible) container_of
macro. So put proper #ifndef protection around our definition of
container_of.
Thanks to Rolf vandeVaart for pointing out the issue.
Reviewed by Dave Goodell.
cmr=v1.7.4:reviewer=ompi-rm1.7
This commit was SVN r29799.