message: Define REALM_DEBUG for spm debug builds
diff: @@ -10,6 +10,7 @@ let versionExtra = versionPieces.count > 1 ? versionPieces[1] : ""
  let cxxSettings: [CXXSetting] = [
  .headerSearchPath("src"),
  + .define("REALM_DEBUG", .when(configuration: .debug)),
  .define("REALM_NO_CONFIG"),
  .define("REALM_INSTALL_LIBEXECDIR", to: ""),
  .define("REALM_ENABLE_ASSERTIONS", to: "1"),
  