btl/sm: re-enable the use of CMA and knem

At some point we added a sanity check to the btl base to ensure that
the btl flags match the available functions (this prevents user's from
specifying get or put when no function exists). This check was
disabling get for the sm btl since at the time of the check there is
no btl_get function. The simplest fix is to set a dummy value to btl_get
that will be overwritten with the proper value on btl initialization.

Closes #239.

opal/mca/btl/sm/btl_sm_component.c

@@ -139,6 +139,9 @@ static int mca_btl_sm_component_verify(void) {
 #if OPAL_BTL_SM_HAVE_KNEM || OPAL_BTL_SM_HAVE_CMA
     if (mca_btl_sm_component.use_knem || mca_btl_sm_component.use_cma) {
         mca_btl_sm.super.btl_flags |= MCA_BTL_FLAGS_GET;
+        /* set a dummy value for btl_get to prevent mca_btl_base_param_verify from
+         * unsetting the MCA_BTL_FLAGS_GET flags. */
+        mca_btl_sm.super.btl_get = (mca_btl_base_module_get_fn_t) 1;
     }
 
     if (mca_btl_sm_component.use_knem && mca_btl_sm_component.use_cma) {