[2726] Suppress another false positive

src/lib/dns/rdata.cc

@@ -309,6 +309,8 @@ Generic::Generic(const Generic& source) :
     Rdata(), impl_(new GenericImpl(*source.impl_))
 {}
 
+// cppcheck-suppress operatorEqToSelf this check is better than
+// this == &source, just that cppcheck doesn't understand it.
 Generic&
 Generic::operator=(const Generic& source) {
     if (impl_ == source.impl_) {