old_contents: {
    "targets": [
      {
        "target_name": "walken",
        "sources": [ "src/walken.cc" ],
      }
    ]
  }
  
new_contents: {
    "targets": [
      {
        "target_name": "walken",
        "sources": [ "src/walken.cc" ],
        "defines": [
          "_FILE_OFFSET_BITS=32"
        ]
      }
    ]
  }
  
subject: Set _FILE_OFFSET_BITS to 32