nameserv: move fallback DNS_Name2IPAddressAsync() to stubs.c

configure

@@ -437,7 +437,7 @@ fi
 
 if [ $feat_ntp = "1" ]; then
   add_def FEAT_NTP
-  EXTRA_OBJECTS="$EXTRA_OBJECTS broadcast.o nameserv_async.o ntp_core.o ntp_io.o ntp_sources.o"
+  EXTRA_OBJECTS="$EXTRA_OBJECTS broadcast.o ntp_core.o ntp_io.o ntp_sources.o"
 else
   feat_asyncdns=0
 fi
@@ -541,6 +541,7 @@ if [ $feat_asyncdns = "1" ] && \
 then
   add_def FEAT_ASYNCDNS
   add_def USE_PTHREAD_ASYNCDNS
+  EXTRA_OBJECTS="$EXTRA_OBJECTS nameserv_async.o"
   MYCFLAGS="$MYCFLAGS -pthread"
 fi
 

nameserv_async.c

@@ -34,8 +34,6 @@
 #include "sched.h"
 #include "util.h"
 
-#ifdef FEAT_ASYNCDNS
-
 #ifdef USE_PTHREAD_ASYNCDNS
 #include <pthread.h>
 
@@ -124,21 +122,3 @@ DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *
 #else
 #error
 #endif
-
-#else
-
-/* This is a blocking implementation used when nothing else is available */
-
-void
-DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
-{
-  IPAddr addr;
-  DNS_Status status;
-
-  status = DNS_Name2IPAddress(name, &addr);
-  (handler)(status, &addr, anything);
-}
-
-/* ================================================== */
-
-#endif

stubs.c

@@ -34,11 +34,28 @@
 #include "logging.h"
 #include "manual.h"
 #include "nameserv.h"
+#include "nameserv_async.h"
 #include "ntp_core.h"
 #include "ntp_io.h"
 #include "ntp_sources.h"
 #include "refclock.h"
 
+#ifndef FEAT_ASYNCDNS
+
+/* This is a blocking implementation used when asynchronous resolving is not available */
+
+void
+DNS_Name2IPAddressAsync(const char *name, DNS_NameResolveHandler handler, void *anything)
+{
+  IPAddr addr;
+  DNS_Status status;
+
+  status = DNS_Name2IPAddress(name, &addr);
+  (handler)(status, &addr, anything);
+}
+
+#endif /* !FEAT_ASYNCDNS */
+
 #ifndef FEAT_CMDMON
 
 void