OpenAPI: make only one tag entry when the state stack is matched

The original code tried matching even after making a tag for a token.

This change is derrived from universal-ctags#3258.
The original commit is so large.
@masatake splited the commit smaller per-topic ones.
@masatake wrote this commit log.

parsers/openapi.c

@@ -249,6 +249,7 @@ static void handleKey(struct sOpenAPISubparser *openapi,
 			attachYamlPosition (&tag, token, false);
 
 			makeTagEntry (&tag);
+			break;
 		}
 	}
 }