Remove dead support for changing BDB hash algorithm and cache of alternatives

ok natano@ millert@ deraadt@

Pull in namespace.h when building all .c files using gcc's -include option,
so that we can provide asm labels for the memcpy/memset/__stack_smash_handler
calls that it generates ab initio. Eliminate

Pull in namespace.h when building all .c files using gcc's -include option,
so that we can provide asm labels for the memcpy/memset/__stack_smash_handler
calls that it generates ab initio. Eliminate direct #includes of it. Make
sure it's a dependency of all objects (unnecessary for asm, but close enough).

ok deraadt@

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Only need <stdint.h> and not all of <inttypes.h> here

use calloc() to avoid malloc(n * m) overflows; checked by djm canacar jsg

fix a few warnings, keep the crypt stuff for later.
okay otto@

zap remaining rcsid.

Kill old files that are no longer compiled.

okay theo

Working hcreate(3) et al from NetBSD (cgd) via ray at cyth dot net.
Now passes the regress tests.