Fail compiles if no platform specific memory barriers exist

Currently there is a "generic" implementation for the memory barrier
macros in arch.h.  These turned out to be insuffient for ARM64 causing
memory corruption problems when doing RDMA operations.  So going forward,
fail a compile on a platform w/o platform-specific memory barrier macros.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>