strerror may be not thread safe
Some libraries used by VLC use strerror() which may be not thread-safe, at least on Linux it is not.
See http://www.opengroup.org/onlinepubs/000095399/functions/strerror.html for correct use of strerror_r()
Ideally all these libs should be patched, the patches put into extras/contrib/src/Patches, and sent to the maintainers.
The problem is that strerror_r() doesn't exist on all platforms, and GNU Libc has a prototype different from POSIX one: char *strerror_r(int errnum, char *buf, size_t buflen);
Note that GLibc strerror_r() may, or may not use the supplied buffer *buf.