libvlc: call exit() if command line help was requested
A library should not call exit(), but I do not see any easy way around it: if libvlc_new() returns NULL on error so real errors cannot be distinguished from --help stuff. Also --daemon already calls exit() (through daemon()). This introduces an O(1) memory leak when calling --help. It could be fixed by merging libvlc_InternalCreate() and libvlc_InternalInit().