Support defines and other settings that come through dump.json

[cgrindel]

Example: https://github.com/apple/swift-crypto/blob/main/Package.swift#L82-L89
WIN32_LEAN_AND_MEAN define comes through as:

    {
      "dependencies" : [

      ],
      "exclude" : [
        "hash.txt",
        "include/boringssl_prefix_symbols_nasm.inc",
        "CMakeLists.txt"
      ],
      "name" : "CCryptoBoringSSL",
      "resources" : [

      ],
      "settings" : [
        {
          "kind" : {
            "define" : {
              "_0" : "WIN32_LEAN_AND_MEAN"
            }
          },
          "tool" : "c"
        }
      ],
      "type" : "regular"
    },

[cgrindel]

Fixed by #92.