configure: make NTP and ASYNCDNS support nonoptional

Don't allow the NTP support and asynchronous name resolving to be
disabled. pthreads are now a hard requirement.

NTP is the primary task of chrony. This functionality doesn't seem to be
commonly disabled (allowing only refclocks and manual input).

This removes rarely (if ever) used code and simplifies testing.

configure

@@ -116,7 +116,6 @@ For better control, use the options below.
   --without-tomcrypt     Don't use libtomcrypt even if it is available
   --disable-nts          Disable NTS support
   --disable-cmdmon       Disable command and monitoring support
-  --disable-ntp          Disable NTP support
   --disable-refclock     Disable reference clock support
   --disable-phc          Disable PHC refclock driver
   --disable-pps          Disable PPS refclock driver
@@ -126,7 +125,6 @@ For better control, use the options below.
   --without-libcap       Don't use libcap even if it is available
   --enable-scfilter      Enable support for system call filtering
   --without-seccomp      Don't use seccomp even if it is available
-  --disable-asyncdns     Disable asynchronous name resolving
   --disable-forcednsretry Don't retry on permanent DNS error
   --without-aes-gcm-siv  Don't use AES-GCM-SIV for NTS even if it is available
   --without-clock-gettime Don't use clock_gettime() even if it is available
@@ -219,7 +217,6 @@ EXTRA_CLI_OBJECTS=""
 
 feat_debug=0
 feat_cmdmon=1
-feat_ntp=1
 feat_refclock=1
 feat_readline=1
 try_editline=1
@@ -243,7 +240,6 @@ try_phc=0
 feat_pps=1
 try_setsched=0
 try_lockmem=0
-feat_asyncdns=1
 feat_forcednsretry=1
 try_aes_gcm_siv=1
 try_clock_gettime=1
@@ -253,7 +249,6 @@ feat_timestamping=1
 try_timestamping=0
 feat_ntp_signd=0
 ntp_era_split=""
-use_pthread=0
 default_user="root"
 default_hwclockfile=""
 default_pidfile="/var/run/chrony/chronyd.pid"
@@ -308,9 +303,6 @@ do
     --disable-cmdmon)
       feat_cmdmon=0
     ;;
-    --disable-ntp)
-      feat_ntp=0
-    ;;
     --disable-refclock)
       feat_refclock=0
     ;;
@@ -341,9 +333,6 @@ do
     --without-seccomp)
       try_seccomp=0
     ;;
-    --disable-asyncdns)
-      feat_asyncdns=0
-    ;;
     --disable-forcednsretry)
       feat_forcednsretry=0
     ;;
@@ -504,22 +493,9 @@ if [ $feat_cmdmon = "1" ]; then
   EXTRA_OBJECTS="$EXTRA_OBJECTS cmdmon.o manual.o pktlength.o"
 fi
 
-if [ $feat_ntp = "1" ]; then
-  add_def FEAT_NTP
-  EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_auth.o ntp_core.o ntp_ext.o ntp_io.o ntp_sources.o"
-  if [ $feat_ntp_signd = "1" ]; then
-    add_def FEAT_SIGND
-    EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_signd.o"
-  fi
-else
-  feat_asyncdns=0
-  feat_timestamping=0
-fi
-
-if [ "$feat_cmdmon" = "1" ] || [ $feat_ntp = "1" ]; then
-  EXTRA_OBJECTS="$EXTRA_OBJECTS addrfilt.o clientlog.o keys.o nameserv.o"
-else
-  feat_ipv6=0
+if [ $feat_ntp_signd = "1" ]; then
+  add_def FEAT_SIGND
+  EXTRA_OBJECTS="$EXTRA_OBJECTS ntp_signd.o"
 fi
 
 if [ $feat_refclock = "1" ]; then
@@ -706,15 +682,15 @@ then
   exit 1
 fi
 
-if [ $feat_asyncdns = "1" ] && \
-  test_code 'pthread' 'pthread.h' '-pthread' '' '
-    pthread_t thread;
-    return (int)pthread_create(&thread, NULL, (void *)1, NULL);'
+if test_code 'pthread' 'pthread.h' '-pthread' '' '
+  pthread_t thread;
+  return (int)pthread_create(&thread, NULL, (void *)1, NULL);'
 then
-  add_def FEAT_ASYNCDNS
   add_def USE_PTHREAD_ASYNCDNS
-  EXTRA_OBJECTS="$EXTRA_OBJECTS nameserv_async.o"
-  use_pthread=1
+  MYCFLAGS="$MYCFLAGS -pthread"
+else
+  echo "error: pthread_create() not found"
+  exit 1
 fi
 
 if [ $try_arc4random = "1" ] && \
@@ -817,12 +793,10 @@ if [ $feat_scfilter = "1" ] && [ $try_seccomp = "1" ] && \
     'seccomp_init(SCMP_ACT_KILL);'
 then
   add_def FEAT_SCFILTER
-  if [ $feat_ntp = "1" ]; then
-    # NAME2IPADDRESS shouldn't be enabled together with a privops operation
-    # used by the main thread as the helper process works on one request at
-    # a time and the async resolver would block the main thread
-    priv_ops="NAME2IPADDRESS RELOADDNS"
-  fi
+  # NAME2IPADDRESS shouldn't be enabled together with a privops operation
+  # used by the main thread as the helper process works on one request at
+  # a time and the async resolver would block the main thread
+  priv_ops="NAME2IPADDRESS RELOADDNS"
   EXTRA_LIBS="$EXTRA_LIBS -lseccomp"
 fi
 
@@ -861,7 +835,6 @@ if [ $try_setsched = "1" ] && \
      pthread_setschedparam(pthread_self(), SCHED_FIFO, &sched);'
 then
   add_def HAVE_PTHREAD_SETSCHEDPARAM
-  use_pthread=1
 fi
 
 if [ $try_lockmem = "1" ] && \
@@ -978,7 +951,7 @@ EXTRA_OBJECTS="$EXTRA_OBJECTS $HASH_OBJ"
 EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS $HASH_OBJ"
 LIBS="$LIBS $HASH_LINK"
 
-if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
+if [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
   if [ "$HASH_OBJ" = "hash_gnutls.o" ]; then
     test_cflags=""
     test_link=""
@@ -1038,10 +1011,6 @@ if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
   fi
 fi
 
-if [ $use_pthread = "1" ]; then
-  MYCFLAGS="$MYCFLAGS -pthread"
-fi
-
 SYSCONFDIR=/etc
 if [ "x$SETSYSCONFDIR" != "x" ]; then
   SYSCONFDIR=$SETSYSCONFDIR
@@ -1107,7 +1076,7 @@ add_def MAIL_PROGRAM "\"$mail_program\""
 
 common_features="`get_features SECHASH IPV6 DEBUG`"
 chronyc_features="`get_features READLINE`"
-chronyd_features="`get_features CMDMON NTP REFCLOCK RTC PRIVDROP SCFILTER SIGND ASYNCDNS NTS`"
+chronyd_features="`get_features CMDMON REFCLOCK RTC PRIVDROP SCFILTER SIGND NTS`"
 add_def CHRONYC_FEATURES "\"$chronyc_features $common_features\""
 add_def CHRONYD_FEATURES "\"$chronyd_features $common_features\""
 echo "Features : $chronyd_features $chronyc_features $common_features"