Log Message:
net/xymonclient: Add DragonFly support / fix FreeBSD

* Add Makefile.DragonFly
* Add xymonclient-dragonfly.sh
* Fix sha2.c #include <stdint.h>.

On last, nothing sets HAVE_STDINT_H and passing -DHAVE_STDINT_H through
cflags fails.  Just switch it based on __FreeBSD__ and __DragonFly__.
There is a placeholder for dragonfly-meminfo.  It's possible that
freebsd-meminfo.c can be used without modification, but it needs
verification before building it.