Use __builtin_setjmp, for MinGW gcc
Use __builtin_setjmp, for MinGW gcc

As per http://www.agardner.me/golang/windows/cgo/64-bit/setjmp/longjmp/2016/02/29/go-windows-setjmp-x86.html

This makes the module build and test 100% OK with Strawberry Perl on Win64
directly from CPAN.

Ideally, the setjmp change would also be communicated to the upstream
Duktape maintainers, but I don't know their build process and how I can
figure out what genconfig.py does.

mamod/JavaScript-Duktape,mamod/JavaScript-Duktape,mamod/JavaScript-Duktape,mamod/JavaScript-Duktape,mamod/JavaScript-Duktape,mamod/JavaScript-Duktape