MDEV-11670: ensure sysconfdir/sysconf2dir are not blank for mariadb@.service

support-files/CMakeLists.txt

@@ -90,8 +90,18 @@ IF(UNIX)
   SET(scriptdir ${INSTALL_SCRIPTDIRABS})
   SET(libexecdir ${INSTALL_SBINDIRABS})
   SET(pkgdatadir ${INSTALL_MYSQLSHAREDIRABS})
-  SET(sysconfdir ${INSTALL_SYSCONFDIR})
-  SET(sysconf2dir ${INSTALL_SYSCONF2DIR})
+  IF(INSTALL_SYSCONFDIR)
+    SET(sysconfdir ${INSTALL_SYSCONFDIR})
+  ELSEIF(DEFAULT_SYSCONFDIR)
+    SET(sysconfdir ${DEFAULT_SYSCONFDIR})
+  ELSE()
+    SET(sysconfdir "/etc")
+  ENDIF()
+  IF(INSTALL_SYSCONFDIR)
+    SET(sysconf2dir ${INSTALL_SYSCONF2DIR})
+  ELSE()
+    SET(sysconf2dir "${sysconfdir}/mysql")
+  ENDIF()
   CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/mysql.server.sh 
                  ${CMAKE_CURRENT_BINARY_DIR}/mysql.server @ONLY)
   INSTALL(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/mysql.server