MS Windows in AppVeyor, Failure To Call gsl-config & swig Commands

[wbraswell]

Howdy @leto & @bulk88 & @jberger,

Below is an overview of the work bulk88 and I have done on this issue so far...

• The previous AppVeyor RPerl build was failing due to missing sh prefix in call to gsl-config shell script:

  https://ci.appveyor.com/project/wbraswell/rperl/builds/24344424?fullLog=true#L9057

• We wrongly thought we needed to install the outdated GnuWin package to provide gsl-config, but this was incorrect because Alien::GSL already correctly builds and installs gsl-config:

  wbraswell/rperl@82ec9f4

  https://ci.appveyor.com/project/wbraswell/rperl/builds/24344424?fullLog=true#L7256

• We temporarily patched Math::GSL in my forked GitHub repo, in order to test our solution which seems to have worked for gsl-config, although it is only a temporary solution with hard-coded values specific to AppVeyor:

  wbraswell/rperl@3fb3771

  wbraswell@0a346f7

• The current AppVeyor RPerl build is now failing due to missing swig binary:

  https://ci.appveyor.com/project/wbraswell/rperl/builds/25408900

• We started working on the swig issue but ran out of time close to 3am the last night of TPCiP, the to-be-determined solution for this issue may or may not be related to the gsl-config solution:

  wbraswell@0979748

• bulk88 now has Alien::GSL and Math::GSL installed on his personal Windows laptop, in order to determine if our solution(s) are correct and robust before making a pull request to leto

[wbraswell]

@bulk88
Please let us know how to proceed, thank you sir! :-)