fallback to the another method to lock when link() failed

Bug 82358 - FcAtomicLock fails on OS X on network mounts
https://bugs.freedesktop.org/show_bug.cgi?id=82358
Increase the refcount in FcConfigSetCurrent()

https://bugs.freedesktop.org/show_bug.cgi?id=82432
Fix the memory leak in fc-cat
Note FcConfigSetCurrent() increases the refcount in document