[ofiwg] detecting FABRIC_DIRECT mismatch

[Hefty, Sean]

We've hit into a situation where libfabric was compiled with FABRIC_DIRECT, but the application was not.  What I'm looking for are ideas for how to detect this situation, so that libfabric can report an appropriate error/log message.  I believe a run time check is preferable.

So far, the ideas are:

- Require providers to always support both modes.  (Extra work on the provider doesn't seem worth it.)
- Set a bit in the major version number to indicate FABRIC_DIRECT.  This would be done automatically via the FI_VERSION macro.
- Add a new FI_FABRIC_DIRECT flag to fi_getinfo.  Maybe this can be handled automatically by changing fi_getinfo into a static inline?  Not sure about this.

- Sean