old_contents: {
    'targets': [
      {
        'target_name': 'binding',
        'sources': [
          'src/binding.cc'
        ],
        'include_dirs': ['<!@(pg_config --includedir)'],
        'libraries' : ['-lpq -L<!@(pg_config --libdir)']
      }
    ]
  }
  
new_contents: {
    'targets': [
      {
        'target_name': 'binding',
        'sources': [
          'src/binding.cc'
        ],
        'conditions' : [
          ['OS=="mac"', {
            'include_dirs': ['<!@(pg_config --includedir)'],
            'libraries' : ['-lpq -L<!@(pg_config --libdir)']
          }],
          ['OS=="linux"', {
            'include_dirs': ['<!@(pg_config --includedir)'],
            'libraries' : ['-lpq -L<!@(pg_config --libdir)']
          }],
          ['OS=="win"', {
            'include_dirs': ['<!@(pg_config --includedir)'],
            'libraries' : ['libpq.dll'],
            'msvs_settings': {
              'VCLinkerTool' : {
                'AdditionalLibraryDirectories' : [
                  '<!@(pg_config --libdir)\\'
                ]
              },
            }
          }]
        ]
      }
    ]
  }
  
subject: Add conditions to the binding.gyp for windows, linux, mac.