Fix unsigned overflow in Debug::Block dtor

Signed-off-by: mio <stigma@disroot.org>
(cherry picked from commit 956d90f8cb)

amarok/src/debug.h

@@ -194,7 +194,10 @@ namespace Debug LIBAMAROK_EXPORT
 
             double duration = double(end.tv_sec) + (double(end.tv_usec) / 1000000.0);
 
-            Debug::modifieableIndent().truncate( Debug::indent().length() - 2 );
+            // Prevent overflow that causes UINT_MAX allocation.
+            uint newLength = (Debug::indent().length() < 2) ? 0 : (Debug::indent().length() - 2);
+            Debug::modifieableIndent().truncate( newLength );
+
             kdDebug() << "END__: " << m_label
                       << " - Took " << TQString::number( duration, 'g', 2 ) << "s\n";
             mutex.unlock();