net-im/ruqola: fix build on FreeBSD 12

/wrkdirs/usr/ports/net-im/ruqola/work/ruqola-1.9.1/src/pimcommontexttranslator/translator/widgets/translatordebugdialog.cpp:91:69: error: use of undeclared identifier 'errno'
                                    QString::fromLocal8Bit(strerror(errno))),
                                                                    ^
1 error generated.