Target not found: mingw-w64-x86_64-libmicroutils

I just installed FF on win10x64. I followed the doc instructions and there’s a little error I couldn’t fix while installing the dependancies : I can’t find the package libmicroutils. Maybe the package is not used anymore but it is still in the doc. I would suggest to modify the doc if it’s the case. Or how could I find it ?
Thanks for your help !

I have never see this package, I will remove from the doc,