MDEV-19210: update galera_new_cluster to use environment file

Now that the systemd unit files use an environment file to pass
_WSREP_START_POSITION we have to update galera_new_cluster as well.

scripts/CMakeLists.txt

@@ -206,6 +206,9 @@ ELSE()
   SET(localstatedir ${MYSQL_DATADIR})
 ENDIF()
 
+get_filename_component(MYSQL_UNIX_DIR ${MYSQL_UNIX_ADDR} DIRECTORY)
+SET(mysqlunixdir ${MYSQL_UNIX_DIR})
+
 SET(resolveip_locations "$basedir/${INSTALL_BINDIR} $basedir/bin")
 SET(mysqld_locations "$basedir/${INSTALL_SBINDIR} $basedir/libexec $basedir/sbin $basedir/bin")
 SET(errmsg_locations "$basedir/${INSTALL_MYSQLSHAREDIR}/english $basedir/share/english $basedir/share/mariadb/english $basedir/share/mysql/english")
@@ -224,6 +227,18 @@ IF(UNIX AND NOT WITHOUT_SERVER)
     COMPONENT Server)
 
   INSTALL_LINK(mariadb-install-db mysql_install_db ${INSTALL_SCRIPTDIR} ServerSymlinks)
+
+  CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/galera_new_cluster.sh
+    ${CMAKE_CURRENT_BINARY_DIR}/galera_new_cluster ESCAPE_QUOTES @ONLY)
+    EXECUTE_PROCESS(
+    COMMAND chmod +x ${CMAKE_CURRENT_BINARY_DIR}/galera_new_cluster
+    )
+
+  INSTALL_SCRIPT(
+   "${CMAKE_CURRENT_BINARY_DIR}/galera_new_cluster"
+    DESTINATION ${INSTALL_SCRIPTDIR}
+    COMPONENT Server
+    )
 ENDIF()
 
 SET(prefix "${CMAKE_INSTALL_PREFIX}")

scripts/galera_new_cluster.sh

@@ -21,11 +21,11 @@ EOF
     exit 0
 fi
 
-systemctl set-environment _WSREP_NEW_CLUSTER='--wsrep-new-cluster' && \
+echo _WSREP_NEW_CLUSTER='--wsrep-new-cluster' > @mysqlunixdir@/"wsrep-new-cluster" && \
     systemctl restart ${1:-mariadb}
 
 extcode=$?
 
-systemctl set-environment _WSREP_NEW_CLUSTER=''
+rm -f @mysqlunixdir@/"wsrep-new-cluster"
 
 exit $extcode