Simplify error handling of string conversion

Unconditionally free heap-allocated buffer, and only set thread
description if MultiByteToWideChar returns a non-zero integer.

Author: hmelder

src/queue.c

@@ -42,15 +42,11 @@ void _dispatch_win32_set_thread_description(HANDLE hThread, const char *descript
     }
 
     int result = MultiByteToWideChar(CP_UTF8, 0, description, -1, wcstr, wcsize);
-    if (result == 0) {
-        free(wcstr);
-        return;
-    }
-
-    if (likely(wcstr != NULL)) {
+    if (result != 0) {
         SetThreadDescription(hThread, wcstr);
-        free(wcstr);
     }
+
+    free(wcstr);
 }
 #endif