Make loplugin:stringadd slightly more aggressive
...by assuming that all const member functions are side-effect free. (This
presumably means that some of the special cases in
StringAdd::isSideEffectFree are obsoleted by this more general case, but any
such removal is postponed to later clean-up.)
(Came across this when idly wondering why
8b7f948d9d79393bc6c1b11d239706666fd5d7de "sc, VmlFormControlExporter: avoid
OStringBuffer style" had not been found by the plugin before.)
Change-Id: I6bca10df53885b14a590543aabd61f23b3748572
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/118675
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>