Update the error message to pinpoint the right location.
Thanks Tim.
OSHMEM: missing APIs are back and can be used.

fixed by Roman, reviewed by MikeD
pml ob1: use the pre-computed size from the free lists

Based on a suggestion from George on #31806, use the pre-computed
sizes rather than duplicating the computation math (which may change
someday in the future).

cmr=v1.8.2:ticket=#4647
OSHMEM: rename atomic fetch&inc  from 'pshmem_*' to 'shmem_*'