fix incorrect comment
fix NULL dereference uncovered by coverity
Make verto_set_flags() a no-op if the flags are not changed.
Fix tevent autodetection symbol name.
Don't use pkg-config to check for libev

Several distributions used to ship a .pc file for libev, but upstream has
ultimately rejected supporting pkg-config. This is causing distros to
remove support for libev.
bump for 0.2.6 release