os_type unix soname_pattern_base "libbotan-{version_major}.{version_minor}.dylib" soname_pattern_abi "libbotan-{version_major}.{version_minor}.{abi_rev}.dylib" soname_pattern_patch "libbotan-{version_major}.{version_minor}.{abi_rev}.{version_patch}.dylib" doc_dir doc arc4random dlopen filesystem gmtime_r readdir sockets threads