Fix a couple of nits which also cause problems on TPF:

- get rid of the "const" in a const void function definition
- prefix BYTE and LONG with AP_ in ap_sha1.[ch]. BYTE is already defined
  on TPF
- prepend a couple of declarations with extern, so they don't end up as
  double definitions.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@83582 13f79535-47bb-0310-9956-ffa450edef68