make the checkds system test dependent on the result of python discovery

bin/tests/system/conf.sh.in

@@ -55,7 +55,7 @@ VERIFY=$TOP/bin/dnssec/dnssec-verify
 # load on the machine to make it unusable to other users.
 # v6synth
 SUBDIRS="acl allow_query addzone autosign builtin cacheclean checkconf
-	 checkds checknames checkzone database dlv dlvauto dlz dlzexternal
+	 @CHECKDS@ checknames checkzone database dlv dlvauto dlz dlzexternal
          dname dns64 dnssec ecdsa forward glue gost ixfr inline limits
 	 logfileconfig lwresd masterfile masterformat metadata notify
 	 nsupdate pending pkcs11 redirect resolver rndc rpz rrsetorder

configure.in

@@ -178,7 +178,7 @@ except: exit(1)'
 			case "$use_python" in
 			unspec)
 				PYTHON=""
-				AC_SUBST(PYTHON)
+				AC_SUBST(CHECKDS)
 				AC_MSG_RESULT([not found, python disabled])
 				;;
 			yes)
@@ -191,9 +191,12 @@ except: exit(1)'
 esac
 
 PYTHON_TOOLS=''
+CHECKDS=''
 if test "X$PYTHON" != "X"; then
         PYTHON_TOOLS=python
+	CHECKDS=checkds
 fi
+AC_SUBST(CHECKDS)
 AC_SUBST(PYTHON_TOOLS)
 
 #