Fix a crash issue when empty strings are set to the BDF properties
Add a doc for FcDirCacheRescan
Add missing #include <sys/statvfs.h> in fcstat.c

https://bugs.freedesktop.org/show_bug.cgi?id=74602
Fix incompatible API on AIX with random_r and initstate_r

https://bugs.freedesktop.org/show_bug.cgi?id=74603