Let CConnection intercept more callbacks

We need more callbacks for correct operation of multi-threaded
rect decoding.
diff --git a/tests/encperf.cxx b/tests/encperf.cxx
index 06c878d..2111608 100644
--- a/tests/encperf.cxx
+++ b/tests/encperf.cxx
@@ -208,6 +208,8 @@
 
 void CConn::framebufferUpdateStart()
 {
+  CConnection::framebufferUpdateStart();
+
   updates.clear();
   startCpuCounter();
 }
@@ -218,6 +220,8 @@
   rfb::PixelBuffer* pb = getFramebuffer();
   rfb::Region clip(pb->getRect());
 
+  CConnection::framebufferUpdateEnd();
+
   endCpuCounter();
 
   decodeTime += getCpuCounter();