flag parsing. Add CW_LST_MNT_OPTS case to allow mount flag listing.
* mount.cc (fstab_read_flags): Rename from read_flags. Make externally
available. Change input string to char ** to allow returning faulty
option. Add flag for avoiding debug output.
(fstab_list_flags): New function to create list of options.
* include/sys/cygwin.h (cygwin_getinfo_types): Add CW_CVT_MNT_OPTS and
CW_LST_MNT_OPTS.