On Windows: Automatically run autoreconf -i when needed

[mpilgrem]

I think this is a stack feature request (and not a bug). It may be a bug if #3598 was intended to work on Windows as it does on Unix-like operating systems.

In a clean clone of the process library from GitHub, on Windows 10 with stack --version Version 2.0.0, Git revision dfbf85ad7e8af5b01cf7b51367290870ffc2c90e (7456 commits) x86_64 hpack-0.31.1 , stack build fails with (extracts):

Trying to generate configure with autoreconf in C:\Users\mikep\Documents\Code\GitHub\process\
Unable to run autoreconf: Executable named autoreconf not found on path: ...

Configuring process-1.6.5.0...
Warning: The 'build-type' is 'Configure' but there is no 'configure' script.
You probably need to run 'autoreconf -i' to generate it.
setup.exe: configure script not found.

Following up, I discovered #3598. I think that feature does not work on Windows because autoreconf is a shell script file, not an executable (I get the same error message even if the autoreconf file is on the path).

My feature request is to make #3598 work for Windows users of stack. That is, automatically run the autoreconf -i script when needed. That would require the stack MSYS2 to come with autoconf and perl (see below).

I could build process on Windows using stack if I did the following:

1. Add both autoconf and perl to stack's MSYS2, using stack exec pacman -- -S. stack's version of MSYS2 does not come with them as standard.
2. Execute stack exec sh -- autoreconf -i.
3. Execute stack build.