ap_rprintf is implemented as API_EXPORT() in http_protocol.c.

  ap_rprintf is implemented as API_EXPORT() in http_protocol.c.
  Therefore, make the prototype and implementation consistant.

  The question remains, why no compiler warning/emit?  Because MSVC [my
  version, at least] must have changed all of the ap_fn(foo, ...) decl
  from _stdcall to _cdecl, on it's own!

  I suggest our declarations are still borked, but they have worked only
  because MSVC ignored our poor judgement :)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@92964 13f79535-47bb-0310-9956-ffa450edef68