Missing VMIME_EXPORT on net::smtp::SMTPResponse::responseLine

[jengelh]

From https://forum.kopano.io/topic/2537/solved-compilation-on-cygwin-problems-with-missing-symbols-in-vmime/ :

/usr/src/debug/kopano-core/inetmapi/MAPISMTPTransport.cpp:223: undefined reference to `vmime::net::smtp::SMTPResponse::responseLine::getText() const'

I believe this happens when invoking:

vmime::shared_ptr<SMTPResponse> resp = obtain_from_somewhere();
resp->getLastLine().getText();

getLastLine() returns a net::smtp::SMTPResponse::responseLine, and this class's symbols are neither exported nor is responseLine::getText virtual (which would sidestep symbol lookup because of the use of VFT).