Remove code to set or reference the length fields of socket addresses
(sa_len/sin_len/sin6_len), since they aren't portable and setting them
is not required.  Remove autoconf tests for those fields which are no
longer used or which were never used.

There is one exception: in localaddr.c, we still neeed to reference
sa_len for the definition of ifreq_size on platforms which have
sa_len.  Leave that behind, along with the autoconf test which defines
SA_LEN.

In socket-utils.h, replace the socklen macro with an inline function
sa_socklen which always uses the address family, even on platforms
with the sa_len sockaddr field.  This removes the need to set sa_len
in socket addresses we construct.

In setup_udp_port_1, remove the haddrbuf parameter and use paddr like
we already do for one of the log messages.  In setup_udp_port, remove
the long switch statement and just look for AF_INET/AF_INET6
addresses.  Split up udp_flags into two booleans for clarity.  Update
the comment in loop_setup_network since we did the "To do" item a long
time ago.

For example, FreeBSD has removed RTM_OLDADD and RTM_OLDDEL from its API
in March 2014, with the message:
Garbage collect long time obsoleted (or never used) stuff from routing API

Only attempt to define behavior for these cases if they are defined.

ticket: 7955 (new)
tags: pullup
target_version: 1.12.2

Use sa_setport and sa_getport in place of existing static helpers or
open-coded switch statements in net-server.c, fake-addrinfo.c, and
svc_tcp.c.

It has been unused since 2009 when Ken decided that the routing log
messages were too verbose (commit 91fc077c96926dd60).

In ure.c, though k is a short, the literal 1 is of type 'int', and
so the operation 'k + 1' is performed at the (32-bit) width of int,
and therefore the "%d" format string is correct.

In accept_sec_context.c, the 'length' field of krb5_data is an
unsigned type, so checking for a negative value has no effect.

In net-server.c, the helper routine rtm_type_name() is only used
in code that is disabled with #if 0 conditionals; make the
definition also disabled in the same way to avoid warnings of an
unused function.

In kdc_authdata.c, equality checks in double parentheses elicit
a warning from clang.  The double-parentheses idiom is normally used
to indicate that an assignment is being performed, but the value of
the assignment is also to be used as the value for the conditional.
Since assignment and equality checking differ only by a single
character, clang considers this worthy of a warning.  Since the extra
set of parentheses is redundant and against style, it is correct to
remove them.

In several places (sim_server.c, dump.c, kdb5_destroy.c,
ovsec_kadmd.c), there are declarations of extern variables relating
to getopt() functionality that are now unused in the code.  Remove
these unused variables.

Provide default values in pre.in for PROG_LIBPATH, PROG_RPATH,
SHLIB_DIRS, SHLIB_RDIRS, and STOBJLISTS so that they don't have to be
specified in the common case.  Rename KRB5_RUN_ENV and KRB5_RUN_VARS
to RUN_SETUP (already the most commonly used name) and RUN_VARS.  Make
sure to use DEFINES for local defines (not DEFS).  Remove some other
unnecessary makefile content.

It's a lot of code, and trace logging should cover most of the cases
where it's useful.