CRASH (Segfault in shared_librayr_error)

_From [zhao...@google.com](https://code.google.com/u/106321947286816917100/) on May 04, 2012 14:16:45_

When fail to load the client library with private loader, a segfault happens.

void
shared_library_error(char _buf, int maxlen)
{
char *err = dlerror();
strncpy(buf, err, maxlen-1);
buf[maxlen-1] = '\0'; /_ strncpy won't put on trailing null if maxes out */
}

This is because dlerror() returns NULL.

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=768_