[travis] Correct configure line for php-libev

Author: igorw

.travis.yml

@@ -10,7 +10,7 @@ before_script:
   - sh -c " if [ \"\$(php --re libevent | grep 'does not exist')\" != '' ]; then
               (yes '' | pecl install libevent-beta)
             fi"
-  - (git clone --recursive https://github.com/m4rw3r/php-libev && cd php-libev && phpize && ./configure && make && make install)
+  - (git clone --recursive https://github.com/m4rw3r/php-libev && cd php-libev && phpize && ./configure --with-libev && make && make install)
   - echo "extension=libev.so" >> `php --ini | grep "Loaded Configuration" | sed -e "s|.*:\s*||"`
   - composer self-update
   - composer install --dev --prefer-source