Fix typo in qwaitcondition_unix.cpp

Change-Id: Ifc1fdaaa05275b6f68a868a2fc8ccc332e5355ce
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

src/corelib/thread/qwaitcondition_unix.cpp

@@ -136,7 +136,7 @@ public:
                 code = pthread_cond_wait(&cond, &mutex);
             }
             if (code == 0 && wakeups == 0) {
-                // many vendors warn of spurios wakeups from
+                // many vendors warn of spurious wakeups from
                 // pthread_cond_wait(), especially after signal delivery,
                 // even though POSIX doesn't allow for it... sigh
                 continue;