yarpgen claims to be compliant with the standard, but is using the gcc extension __typeof__

Section 3 in the included document (yarpgen-ooplsa-2020.pdf) claims,
that yarpgen can generate C source,
that is "compliant with the rules specified in the language standards".

But the code is using ```__typeof__``` (in the macros ```max``` and ```min```), which is a non standard gcc extension.

A similar feature ```typeof``` was accepted for the upcoming C23 standard,
but that feature is not implemented in all compiler for some time.