configure: fix building with -NTP -CMDMON +SCFILTER

Don't enable privileged operations using the nameserv code unless
NTP is enabled.

configure

@@ -804,10 +804,12 @@ if [ $feat_scfilter = "1" ] && [ $try_seccomp = "1" ] && \
     'seccomp_init(SCMP_ACT_KILL);'
 then
   add_def FEAT_SCFILTER
-  # NAME2IPADDRESS shouldn't be enabled with other operations as the helper
-  # process works on one request at the time and the async resolver could
-  # block the main thread
+  if [ $feat_ntp = "1" ]; then
+    # NAME2IPADDRESS shouldn't be enabled together with a privops operation
+    # used by the main thread as the helper process works on one request at
+    # a time and the async resolver would block the main thread
     priv_ops="NAME2IPADDRESS RELOADDNS"
+  fi
   EXTRA_LIBS="$EXTRA_LIBS -lseccomp"
 fi
 

stubs.c

@@ -49,7 +49,7 @@
 #include "sched.h"
 #include "util.h"
 
-#ifndef FEAT_ASYNCDNS
+#if defined(FEAT_NTP) && !defined(FEAT_ASYNCDNS)
 
 /* This is a blocking implementation used when asynchronous resolving is not available */
 

test/compilation/001-features

@@ -17,12 +17,15 @@ for opts in \
 	"--disable-rtc" \
 	"--disable-sechash" \
 	"--disable-cmdmon" \
+	"--disable-cmdmon --enable-scfilter" \
 	"--disable-ntp" \
+	"--disable-ntp --enable-scfilter" \
 	"--disable-nts" \
 	"--disable-refclock" \
 	"--disable-timestamping" \
 	"--disable-timestamping --disable-ntp" \
 	"--disable-cmdmon --disable-ntp" \
+	"--disable-cmdmon --disable-ntp --enable-scfilter" \
 	"--disable-cmdmon --disable-refclock" \
 	"--disable-cmdmon --disable-ntp --disable-refclock"
 do