COMP: ExternalProject - set git_EXECUTABLE using Git_EXECUTABLE if already defined

Added to avoid to reconfigure exiting dashboard

CMake/ExternalProject.cmake

@@ -771,6 +771,10 @@ function(_ep_add_download_command name)
     list(APPEND depends ${stamp_dir}/${name}-svninfo.txt)
   elseif(git_repository)
     #find_package(Git)
+    # Legacy - Some dashboard are configured using Git_EXECUTABLE
+    if(DEFINED Git_EXECUTABLE)
+      set(git_EXECUTABLE ${Git_EXECUTABLE})
+    endif()
     find_program(git_EXECUTABLE NAMES git.cmd git eg.cmd eg DOC "git command line client")
     if(NOT git_EXECUTABLE)
       message(FATAL_ERROR "error: could not find git for clone of ${name} - Make sure git_EXECUTABLE is set properly")