[2202] Unify class-struct

It should be the same according to the standard, but Clang seems not to
agree with that.

diff --git a/src/lib/util/threads/lock.h b/src/lib/util/threads/lock.h
index 10a7878afa6fb27e469fafd2f923150e7ef5de2d..2c2dab866b568a27b1a833cc6d8268a89dd009eb 100644 (file)
--- a/src/lib/util/threads/lock.h
+++ b/src/lib/util/threads/lock.h
@@ -125,7 +125,7 @@ public:
     bool locked() const;
 private:
     friend class Locker;
-    struct Impl;
+    class Impl;
     Impl* impl_;
     void lock();
     void unlock();