Use the non-deprecated MX_PROCESS_TERMINATED spelling

Change-Id: Icd9fb9079af42fd663233b08ab98533b9f0c8671
diff --git a/benchmarks/spec_fixture.cc b/benchmarks/spec_fixture.cc
index abc8b9c..ac24182 100644
--- a/benchmarks/spec_fixture.cc
+++ b/benchmarks/spec_fixture.cc
@@ -207,7 +207,7 @@
     return status;
   }
   status =
-      mx_object_wait_one(handle, MX_PROCESS_SIGNALED, MX_TIME_INFINITE, NULL);
+      mx_object_wait_one(handle, MX_PROCESS_TERMINATED, MX_TIME_INFINITE, NULL);
 
   if (status != MX_OK) {
     LOG(ERROR) << "Failed to wait for process exiting " << args[0] << ":"