Sync with 2.4.x.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x-mod_md@1820360 13f79535-47bb-0310-9956-ffa450edef68

diff --cc modules/ssl/ssl_engine_init.c
index 2c26564126e4d10c66831d8f7457638e1220d993,f6c51a49b5c5fe0fbb8b27e0af67b5e97bf03653..0cfa766da47bd5b65d77db373e54d1d16706ad01
--- 1/modules/ssl/ssl_engine_init.c
--- 2/modules/ssl/ssl_engine_init.c
+++ b/modules/ssl/ssl_engine_init.c
@@@ -30,8 -30,23 +30,24 @@@
  #include "mod_ssl.h"
  #include "mod_ssl_openssl.h"
  #include "mpm_common.h"
 +#include "mod_md.h"
  
+ /* Use the header, once mod_md is backported. break the dependency loop for now. */
+ #define MOD_MD_BACKPORTED   0
+ #if MOD_MD_BACKPORTED
+ #include "mod_md.h"
+ #else 
+ APR_DECLARE_OPTIONAL_FN(int, 
+                         md_is_managed, (struct server_rec *));
+ APR_DECLARE_OPTIONAL_FN(apr_status_t, 
+                         md_get_certificate, (struct server_rec *, apr_pool_t *,
+                                              const char **pkeyfile, 
+                                              const char **pcertfile));
+ APR_DECLARE_OPTIONAL_FN(int, 
+                         md_is_challenge, (struct conn_rec *, const char *,
+                                           X509 **pcert, EVP_PKEY **pkey));
+ #endif
+ 
  APR_IMPLEMENT_OPTIONAL_HOOK_RUN_ALL(ssl, SSL, int, init_server,
                                      (server_rec *s,apr_pool_t *p,int is_proxy,SSL_CTX *ctx),
                                      (s,p,is_proxy,ctx), OK, DECLINED)