problem: configure for DragonFly need FreeBSD also defined

solution: on DragonFly also define ZMQ_HAVE_FREEBSD
          in addition to ZMQ_HAVe_DRAGONFLY
Signed-off-by: Christopher Hall <hsw@ms2.hinet.net>

builds/cmake/platform.hpp.in

@@ -75,10 +75,15 @@
   #define ZMQ_HAVE_MINGW32
 #endif
 
-#if defined(__FreeBSD__) || defined(__DragonFly__) || defined(__FreeBSD_kernel__)
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
   #define ZMQ_HAVE_FREEBSD
 #endif
 
+#if defined(__DragonFly__)
+  #define ZMQ_HAVE_FREEBSD
+  #define ZMQ_HAVE_DRAGONFLY
+#endif
+
 #if defined __hpux
   #define ZMQ_HAVE_HPUX
 #endif

configure.ac

@@ -233,6 +233,7 @@ case "${host_os}" in
         ;;
     *dragonfly*)
         CPPFLAGS="-D__BSD_VISIBLE $CPPFLAGS"
+        AC_DEFINE(ZMQ_HAVE_FREEBSD, 1, [Have DragonFly OS])
         AC_DEFINE(ZMQ_HAVE_DRAGONFLY, 1, [Have DragonFly OS])
         ;;
     *darwin*)