Change fatal/fatalx to use a format string.  Expand in a static buffer
to cope with low-memory situations.

ok gilles@ chl@
getentropy for osx and solaris. will be needed for a portable release
fatalx(errorstr) -> fatalx("%s", errorstr)
add missing include and remove redundant debug trace while here.
We have EAI_FAMILY - remove the #ifdefs.

ok beck@
Pretty much everything has SO_REUSEADDR - nuke the #ifdefs.

ok beck@
We do not care about broken Borland C pre-processors.

ok beck@ deraadt@