file(GLOB) does not escape filenames with semicolons when creating the output variable definition

We recently stumped against an escaping problem in CMake. GLOBbing a folder to get all filenames creates a list with the wrong number of items if any filename contains semicolons. Things also behave weirdly when square brackets are involved.

To reproduce try the following:

1. Create an empty folder
2. Run the following:

     echo 0 > 'a'
     echo 1 > 'a b '
     echo 2 > 'a;b c'  
     echo 3 > 'a;[;]c'
     echo 4 > 'a;[;c'

3. Use the following CMakeLists.txt in the directory:

     cmake_minimum_required(VERSION 3.11)
     
     file(GLOB files "a*")
     message(STATUS " ++++ ${files} ++++")
     foreach(file IN LISTS files)
       message(STATUS " ------------- ${file} ------------- ")
       file(READ "${file}" contents)
       message("${contents}")
     endforeach()

The culprit seems to be bool cmFileCommand::HandleGlobCommand(std::vector<std::string> const& args, bool recurse). At the end of the method it does: this->Makefile->AddDefinition(variable, cmJoin(files, ";").c_str());.

The contents of the "files" vector should instead be escaped before joining it.