-only enable developer logic if MHD is recent enough

configure.ac

@@ -362,6 +362,8 @@ AC_MSG_RESULT($enable_developer)
 AM_CONDITIONAL([HAVE_DEVELOPER], [test "x$enable_developer" = "xyes"])
 enable_dev=1
 AS_IF([test "x$enableval" = "xno"], [enable_dev=0])
+# developer-logic requires a more recent MHD than usual.
+AC_CHECK_DECL([MHD_OPTION_NOTIFY_CONNECTION],,[enable_dev=0],[[#include <microhttpd.h>]])
 AC_DEFINE_UNQUOTED([HAVE_DEVELOPER],[$enable_dev],[1 if developer logic is enabled, 0 otherwise])
 
 

src/exchange/taler-exchange-httpd.c

@@ -691,6 +691,7 @@ exchange_serve_process_config ()
 /* Developer logic for supporting the `-f' option. */
 #if HAVE_DEVELOPER
 
+
 /**
  * Option `-f' (specifies an input file to give to the HTTP server).
  */
@@ -797,7 +798,6 @@ connection_done (void *cls,
 /* end of HAVE_DEVELOPER */
 #endif
 
-
 /**
  * Function called for logging by MHD.
  *