Initialize sm global variables in mca_btl_sm_component_open(), because they are destructed in mca_btl_sm_component_close(), and init() function might not be called or fail.
For exammple, mca_btl_sm.knem_fd remained 0, and mca_btl_sm_component_close() ended up doing closing fd 0 which belongs to someone else.

fixed by Yossi, reviewed by miked
cmr=v1.7.4:reviewer=ompi-rm1.7