Call bug5452 fix a feature; note its trac number in the changes file

changes/bug5452

@@ -1,4 +1,4 @@
-  o Minor bugfixes:
+  o Minor features:
     - Check CircuitBuildTimeout and LearnCircuitBuildTimeout in
       options_validate(); warn if LearnCircuitBuildTimeout is disabled
-      and CircuitBuildTimeout is set unreasonably low.
+      and CircuitBuildTimeout is set unreasonably low. Fixes bug 5452.