Make call setUUID optional in decryptVerify_o
* src/mail.h: add new version of decryptVerify_o with a new parameter setUUID * src/mail.cpp: move code of decryptVerify_o to new version of the functions and call it from the old version with setUUID set to true. * src/mailitem-event.cpp: use the new version of the function with setUUID set to false as we just called setUUID ourself.
- Adding this option removes calling code that
will "gracefuly fail" as the call was not needed
and reduces clutter in the log.