Merge branch 'release/1.2.5'
Fix double free for evthr at shutdown

If you use threads, than you get this segfault.

There was two calls to evthr_free() on shutdown:
- _evthr_loop() (droped in this patch)
- evthr_pool_free()
Merge branch 'fix-double-free-for-evthr-v2' of git://github.com/azat/libevhtp into azat-fix-double-free-for-evthr-v2