Gah; we need to have a unique barrier ID for the ompi_rte_barrier()
operation.  Ralph will fix shortly.

For the time being, put back the original code...

Refs #4669
Turns out that valgrind has issues with strings that don't fall on nice 4-byte alignments with some optimized builds. So make the default security credential a nice 7-characters (so we get 8-bytes with the NULL terminator) to make valgrind shut up.

Thanks to Walter Spector for reporting this.

cmr=v1.8.2:reviewer=jsquyres:subject=align the default sec credential