Revert an errant part of a previous cleanup, to fix a memory corruption issue.

(closes issue #16368)
 Reported by: thirionjwf
 Patches: 
       res_speech.c.patch uploaded by thirionjwf (license 955)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@247841 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_speech.c

@@ -313,8 +313,9 @@ int ast_speech_unregister(const char *engine_name)
 			/* We have our engine... removed it */
 			AST_RWLIST_REMOVE_CURRENT(list);
 			/* If this was the default engine, we need to pick a new one */
-			if (!default_engine)
+			if (engine == default_engine) {
 				default_engine = AST_RWLIST_FIRST(&engines);
+			}
 			ast_verb(2, "Unregistered speech recognition engine '%s'\n", engine_name);
 			/* All went well */
 			res = 0;