More information in the Paths_pkg.hs module, or a new module

(Imported from [Trac #399](http://hackage.haskell.org/trac/hackage/ticket/399), reported by @dcoutts on 2008-11-08)

There is more information about the system or about the package or configuration that we could include into a generated module.

For example:

• OS name (from standard enum names, not System.Info.os)
  
• Arch name (similarly)
  
• Compiler used for build
  
• Package version (perhaps moved out of the Paths_ module)
  
• Other .cabal file package details (as Strings)
  
  • x-foo extension fields
    
  • license enum
    
  • authors, copyright
    
  • synopsis / description
    
  • home page, bug report url
    
  • configuration flag values
    
• System details
  
  • big or little endian
    
• Revision control context
  
  • git hash
    
  • darcs context