make kleopatra compile without assuan Use macro_optional_find_package, so Assuan support can be switched off using -DWITH_Assuan=no (as suggested by Allen) I suggest to always have no-assuan build dir around to ensure kleopatra builds without assuan, too BUG:156350 CCMAIL:marc@kdab.net

svn path=/trunk/KDE/kdepim/kleopatra/; revision=773956