Configure error when installing FLTK library

  autoconf, c++, fltk, msys2

I’m using Windows with Mingw, installed on path C:mingw-w64
I installed Msys2 on C:msys64

Now I want to install FLTK following the guidelines from here:

But at the configure command I get this error:

$ ./configure
configure: loading site script /etc/
configure: error: cannot run /bin/sh ./config.sub

What should I do? Thanks!

It seems I can run /bin/sh (I don’t get any error, but no other message either). But config.sub doesn’t exist…

Source: Windows Questions C++