Skip libev tests if pyev is not installed or if they are being run in pypy
Skip libev tests if pyev is not installed or if they are being run in pypy

Minor change to how tests are structured and skipped

zixiliuyue/pika,vrtsystems/pika,knowsis/pika,Zephor5/pika,Tarsbot/pika,renshawbay/pika-python3,hugoxia/pika,jstnlef/pika,fkarb/pika-python3,skftn/pika,vitaly-krugl/pika,shinji-s/pika,benjamin9999/pika,reddec/pika,pika/pika