Re: How to test for native JSON support?

[Nikolay Kudryavtsev]

json-serialize would return nil if libjansson library is not available 
during the execution time. So the scenario would be someone building 
Emacs with json support, then forgetting to put libjansson on his path 
and/or moving the binary to another machine. Not very likely to happen 
on any POSIX systems, but a more or less tangible case on Windows.