Interoperability: shmem_query_interoperability API

[minsii]

The shmem_query_interoperability API can be used to query whether an interoperability feature is supported or any constraint is required by the OpenSHMEM implementation in order to support a hybrid "OpenSHMEM+X" program. For instance, it can be used to expose the additional rules of thread-safety in a hybrid OpenSHMEM+MPI program (see description in PR #304).

This API was discussed in issue #243 and PR #304.