Bugfix openmpi about osdeps etc 

here is an openmpi easyconfigs cleanup, triggered by the need to actually use osdeps, correctly.

The points that SHOULD be reviewed as non-trivial are:
* `--with-hwloc=$EBROOTHWLOC` was missing from the `iccifort` case
* Use `shared_lib_ext` for `OpenMPI-1.6.5-GCC-4.7.2`