mandoc -Tlint fixes from <kaspars at bankovskis dot net>
restructure libc/string + libc/arch/*/string coperation regarding
(potentially) MD versions (function dependent, not filename dependent)
split out memcpy/memmove/bcopy and strchr/index/strrchr/rindex
Bring back amd64 .S versions

And the final touch: switch all architectures temporarily to MI
memcpy.c, which contains syslog + abort for overlapping copies.  A nice
harsh undefined behaviour.  We will clean the entire userland of the
remaining issues in this catagory, then switch to the optimised memcpy
which skips the memmove check.

I tried to cut this change into pieces, but testing each sub-step on
every architecture is too time consuming and mindnumbing.
ok miod
move the description of flags from the SYNOPSIS to the DESCRIPTION;
from <kaspars at bankovskis dot net>, minimally tweaked by me;
ok guenther@ jmc@
obvious STANDARDS update
Replace all 14 instances of .St -ansiC-99 in our tree with .St -isoC-99.
The former is not used anywhere in NetBSD, FreeBSD, or DragonFly
and not supported by groff, so i'm going to delete it from mandoc(1).
We don't need two macros for the same thing.
do not use .St -p1003.1d-99 which is used in exactly two pages;
im going to delete support for it from mandoc(1)
update STANDARDS; ok millert@ jmc@
Fix a minor documentation bug: When given the old real ID unchanged,
it is assigned to the saved ID even if no new effective ID is given,
but the existing effective ID differs from the saved ID.
Update STANDARDS and purge the redundant CAVEATS section.
OK millert@ jmc@, no objections from tedu@