osc_sm_passive_target.c: update the check for lock types

Based on some on-list and IM discussion with @hjelmn about
open-mpi/ompi@40b7643119, change the testing to a switch/case.  If we
fall into the default case, assert() error (because it's an OMPI
developer programming error).

ompi/mca/osc/sm/osc_sm_passive_target.c

@@ -151,18 +151,34 @@ ompi_osc_sm_unlock(int target,
     /* ensure all memory operations have completed */
     opal_atomic_mb();
 
-    if (lock_none == module->outstanding_locks[target]) {
+    switch (module->outstanding_locks[target]) {
+    case lock_none:
         return OMPI_ERR_RMA_SYNC;
-    }
 
-    if (module->outstanding_locks[target] == lock_nocheck) {
+    case lock_nocheck:
         ret = OMPI_SUCCESS;
-    } else if (module->outstanding_locks[target] == lock_exclusive) {
+        break;
+
+    case lock_exclusive:
         ret = end_exclusive(module, target);
-    } else if (module->outstanding_locks[target] == lock_shared) {
+        break;
+
+    case lock_shared:
         ret = end_shared(module, target);
-    } else {
-        ret = OMPI_SUCCESS;
+        break;
+
+    default:
+        // This is an OMPI programming error -- cause some pain.
+        assert(module->outstanding_locks[target] == lock_none ||
+               module->outstanding_locks[target] == lock_nocheck ||
+               module->outstanding_locks[target] == lock_exclusive ||
+               module->outstanding_locks[target] == lock_shared);
+
+         // In non-developer builds, assert() will be a no-op, so
+         // ensure the error gets reported
+        opal_output(0, "Unknown lock type in ompi_osc_sm_unlock -- this is an OMPI programming error");
+        ret = OMPI_ERR_BAD_PARAM;
+        break;
     }
 
     module->outstanding_locks[target] = lock_none;