build - Rewire secure, remove conflicts from libmd, libcrypt

build - Rewire secure, remove conflicts from libmd, libcrypt

* Remove /usr/src/secure, folding all of its subsystems into
  /usr/src.  There's no point having a /usr/src/secure any more,
  the system won't run without the secure stuff, the idea that some foreign
  actor could segregate it in order to legally download code without crypto
  is absurd on the modern internet, and the U.S. government stopped caring
  decades ago.

* Remove conflicts from libmd and libcrypt.  Essentially this removes
  the SHA*_*() and MD5_*() APIs from libmd because these APIs already
  exist in lib[re]ssl.

  The older SHA*() and MD5*() APIs are partially retained for legacy base
  code, but will be removed in a later stage (moved to direct-linking the
  needed support source).

  Conflicting routines in libcrypt have been renamed and internalized to
  be libcrypt-only.

* Major rewiring of the Makefile's to support the changes.