check for non-null entry

This commit was SVN r1206.

src/mca/pml/teg/src/pml_teg.c

@@ -119,10 +119,12 @@ int mca_pml_teg_control(int param, void* value, size_t size)
 {
     size_t i=0;
     for(i=0; i<mca_pml_teg.teg_num_ptl_modules; i++) {
+        if(NULL != mca_pml_teg.teg_ptl_modules[i]->ptlm_control) {
             int rc = mca_pml_teg.teg_ptl_modules[i]->ptlm_control(param,value,size);
             if(rc != OMPI_SUCCESS)
                 return rc;
         }
+    }
     return OMPI_SUCCESS;
 }