things to ignore
added a local implementation of htole16

The macros in <endian.h>, such as htole16, are not common to
all POSIX systems.  I've cribbed the non-optimized implementation
from Linux and placed it here.  You can use the optimized versions by
defining HAVE_ENDIAN_H at compile time.
use shift operator instead of binary literals

binary literals (0bxxxxxxxx) are not universally supported.  I've
replaced the binary literals in fts.c with the corresponding shift
operations.
You can't always use %ld for off_t

Depending on your operating system, off_t may be 32 bits (%ld) or may be
64 bits (%lld).  It's easiest to cast it to a (long long) and just use
%lld in all cases.

See the discussion here:

  http://stackoverflow.com/questions/586928/how-should-i-print-types-like-off-t-and-size-t
Make sysconfdir settable via -D (or #define)

This allows one to set the location of the configuration directory
(by default /etc/fido/mfreq) to another path during compile time.
add support for DESTDIR