MDEV-20570 : Packaging fails "The specified timestamp server either could not be reached"

On  Windows, during packaging step, if signing fails, retry
signtool again without timestamp parameter.

Fixes sporadic (rare) failures on buildbot

cmake/sign.cmake.in

@@ -1,13 +1,31 @@
+# If timestamping is used, it can (rarely) fail, when public timestamping service has issues.
+#
+# To handle the error gracefully and tranparently, we'll retry the signtool command,
+# second time without "/t URL" parameter
+SET(SIGNTOOL_PARAMETERS_NO_TIMESTAMP "@SIGNTOOL_PARAMETERS@")
+LIST(FIND SIGNTOOL_PARAMETERS_NO_TIMESTAMP /t idx)
+IF(NOT(idx EQUAL -1))
+ LIST(REMOVE_AT SIGNTOOL_PARAMETERS_NO_TIMESTAMP ${idx})
+ #remove the URL following /t , as well
+ LIST(REMOVE_AT SIGNTOOL_PARAMETERS_NO_TIMESTAMP ${idx})
+ENDIF()
+
+GET_FILENAME_COMPONENT(SIGNTOOL_DIR "@SIGNTOOL_EXECUTABLE@" DIRECTORY)
+GET_FILENAME_COMPONENT(SIGNTOOL_NAME "@SIGNTOOL_EXECUTABLE@" NAME)
+
 FILE(GLOB_RECURSE files "@CMAKE_BINARY_DIR@/*.signme")
 MESSAGE(STATUS "signing files")
+
+
 FOREACH(f ${files})
   STRING(REPLACE ".signme" "" exe_location "${f}")
 
   string (REPLACE ";" " " params "@SIGNTOOL_PARAMETERS@")
-  #MESSAGE("@SIGNTOOL_EXECUTABLE@" sign ${params} "${exe_location}")
 
   EXECUTE_PROCESS(COMMAND
-    "@SIGNTOOL_EXECUTABLE@" sign @SIGNTOOL_PARAMETERS@ "${exe_location}"
+     cmd /c "${SIGNTOOL_NAME}" sign @SIGNTOOL_PARAMETERS@ "${exe_location}" 2>NUL
+     || "${SIGNTOOL_NAME}" sign ${SIGNTOOL_PARAMETERS_NO_TIMESTAMP} "${exe_location}"
+     WORKING_DIRECTORY ${SIGNTOOL_DIR}
      RESULT_VARIABLE ERR)
   IF(NOT ${ERR} EQUAL 0)
     MESSAGE( "Error ${ERR} signing ${exe_location}")