fixes to OpenMPI easyconfigs

* make sanity check less strict, to fix build on e.g. OS X
* do what `-no-OFED` versionsuffix suggests: specify to build OpenMPI without OpenIB/UDAPL support

This would warrant a `goalf/1.1.0` toolchain easyconfig, but we're not going there, `goolf` (or `goof`) will be the way to go from now on.