Fix check for find changes at DDL files (#21)

After commit 97f1f9b all DDL files
were moved to directory "control/ddl". At upgrade test there is check,
which finds diff at DDL files from last release version. Path, where
DDL files are found, was not changed, and this check did not work.

upgrade_test/CMakeLists.txt

@@ -37,12 +37,12 @@ exec_program(
 )
 
 # check whether DDL file (*.sql) is modified
-file(GLOB ddl_files ${CMAKE_SOURCE_DIR}/*.sql)
+file(GLOB ddl_files ${CMAKE_SOURCE_DIR}/control/ddl/*.sql)
 foreach(ddl IN LISTS ddl_files)
   cmake_path(GET ddl FILENAME ddl)
   exec_program(
     git ${CMAKE_SOURCE_DIR} ARGS
-    diff ${latest_tag} --exit-code ${ddl}
+    diff ${latest_tag} --exit-code control/ddl/${ddl}
     OUTPUT_VARIABLE NULL
     RETURN_VALUE "${ddl}_modified")