[petsc-dev] How to deal with OS-specific include paths?

[Karl Rupp]

Hi guys,

some packages such as OpenCL and OpenGL may be located in different 
subfolders depending on which OS we're on:
  Mac OS: OpenCL/*.h   and    OpenGL/*.h
  other:      CL/*.h   and        GL/*.h
How is this properly translated into BuildSystem-specific package files? 
In opengl.py I only find
     self.includes          = ['OpenGL/gl.h']
and I can confirm that it fails to find the headers on my machine (Linux 
Mint). However, if I change the line in opengl.py to ['GL/gl.h'], 
everything works as expected.

So, the question is: How to deal with these OS-specific things? Within 
header files there is the standard
  #if defined(__APPLE__)
approach, but how does this translate to BuildSystem?

Best regards,
Karli