Restore the xmalloc(), xcalloc(), xreallocarray() and xstrdup() changes.
OK deraadt@

backout last week of csh diffs. They are disasterously broken, on i386
it becomes entirely unusable.

strsave() is hard-fail strdup() so simplify and rename to xstrdup().
with help from martijn@.

ok millert@ martijn@

blkfree() takes no action for NULL pointer so callers can avoid checking.

ok jca@

Passing NULL to free() is fine; from Michael W. Bombardieri.

Replace handrolled xfree() function by directly using free(3)

OK mmcc@

delete many more ptr_t casts

incorrect range check, > vs >=, on the error list, spotted by parfait
ok otto jsg

rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable). these days, people use source. these id's do not provide
any benefit, and do hurt the small install media
(th

rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable). these days, people use source. these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

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documentation tweaks.

ok (some time ago) jmc@

off-by-one; inspired by a netbsd coverity fix; ok deraadt@

de-register and ansify functions

Remove the advertising clause in the UCB license which Berkeley
rescinded 22 July 1999. Proofed by myself and Theo.

We live in an ANSI C world. Remove lots of gratuitous #ifdef __STDC__ cruft.

prevent core dumps when stderror() is called before reslab is initialized

spelling

err.[ch] -> error.[ch] and fix err/warn usage.