Add --waiver-multiline for context-sensitive --waiver-output.

src/V3Error.cpp

@@ -117,6 +117,8 @@ void V3ErrorGuarded::suppressThisWarning() VL_REQUIRES(m_mutex) {
 // cppcheck-has-bug-suppress constParameter
 void V3ErrorGuarded::v3errorEnd(std::ostringstream& sstr, const string& extra)
     VL_REQUIRES(m_mutex) {
+    // 'extra' is appended to the message, and is is excluded in check for
+    // duplicate messages. Currently used for reporting instance name.
 #if defined(__COVERITY__) || defined(__cppcheck__)
     if (m_errorCode == V3ErrorCode::EC_FATAL) __coverity_panic__(x);
 #endif