Migrate syn to monorepo.

Bug: http://b/339424309
Test: treehugger
Change-Id: I2f35c0b06d549294094e374e9dbd2937baf43987
diff --git a/Android.bp b/Android.bp
index b0265c3..96beb97 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,42 +1 @@
-// This file is generated by cargo_embargo.
-// Do not modify this file because the changes will be overridden on upgrade.
-
-package {
-    default_applicable_licenses: ["external_rust_crates_syn_license"],
-}
-
-license {
-    name: "external_rust_crates_syn_license",
-    visibility: [":__subpackages__"],
-    license_kinds: ["SPDX-license-identifier-Apache-2.0"],
-    license_text: ["LICENSE"],
-}
-
-rust_library_host {
-    name: "libsyn",
-    host_cross_supported: false,
-    crate_name: "syn",
-    cargo_env_compat: true,
-    cargo_pkg_version: "2.0.38",
-    crate_root: "src/lib.rs",
-    edition: "2021",
-    features: [
-        "clone-impls",
-        "default",
-        "derive",
-        "extra-traits",
-        "full",
-        "parsing",
-        "printing",
-        "proc-macro",
-        "quote",
-        "visit",
-        "visit-mut",
-    ],
-    rustlibs: [
-        "libproc_macro2",
-        "libquote",
-        "libunicode_ident",
-    ],
-    compile_multilib: "first",
-}
+// This crate has been migrated to external/rust/android-crates-io.
diff --git a/TEST_MAPPING b/TEST_MAPPING
deleted file mode 100644
index 7c46892..0000000
--- a/TEST_MAPPING
+++ /dev/null
@@ -1,167 +0,0 @@
-// Generated by update_crate_tests.py for tests that depend on this crate.
-{
-  "imports": [
-    {
-      "path": "external/rust/crates/anyhow"
-    },
-    {
-      "path": "external/rust/crates/arbitrary"
-    },
-    {
-      "path": "external/rust/crates/argh"
-    },
-    {
-      "path": "external/rust/crates/async-stream"
-    },
-    {
-      "path": "external/rust/crates/base64"
-    },
-    {
-      "path": "external/rust/crates/bitflags"
-    },
-    {
-      "path": "external/rust/crates/bytes"
-    },
-    {
-      "path": "external/rust/crates/coset"
-    },
-    {
-      "path": "external/rust/crates/either"
-    },
-    {
-      "path": "external/rust/crates/futures-channel"
-    },
-    {
-      "path": "external/rust/crates/futures-executor"
-    },
-    {
-      "path": "external/rust/crates/futures-test"
-    },
-    {
-      "path": "external/rust/crates/futures-util"
-    },
-    {
-      "path": "external/rust/crates/hashbrown"
-    },
-    {
-      "path": "external/rust/crates/hashlink"
-    },
-    {
-      "path": "external/rust/crates/jni"
-    },
-    {
-      "path": "external/rust/crates/libm"
-    },
-    {
-      "path": "external/rust/crates/libsqlite3-sys"
-    },
-    {
-      "path": "external/rust/crates/oid-registry"
-    },
-    {
-      "path": "external/rust/crates/rand_chacha"
-    },
-    {
-      "path": "external/rust/crates/serde"
-    },
-    {
-      "path": "external/rust/crates/serde-xml-rs"
-    },
-    {
-      "path": "external/rust/crates/serde_cbor"
-    },
-    {
-      "path": "external/rust/crates/slab"
-    },
-    {
-      "path": "external/rust/crates/tinytemplate"
-    },
-    {
-      "path": "external/rust/crates/tinyvec"
-    },
-    {
-      "path": "external/rust/crates/tokio"
-    },
-    {
-      "path": "external/rust/crates/tokio-test"
-    },
-    {
-      "path": "external/rust/crates/unicode-bidi"
-    },
-    {
-      "path": "external/rust/crates/unicode-xid"
-    },
-    {
-      "path": "external/rust/crates/url"
-    },
-    {
-      "path": "external/rust/crates/virtio-drivers"
-    },
-    {
-      "path": "external/rust/crates/zerocopy"
-    },
-    {
-      "path": "external/rust/crates/zeroize"
-    },
-    {
-      "path": "external/uwb/src"
-    },
-    {
-      "path": "packages/modules/DnsResolver"
-    },
-    {
-      "path": "packages/modules/Virtualization/apkdmverity"
-    },
-    {
-      "path": "packages/modules/Virtualization/authfs"
-    },
-    {
-      "path": "packages/modules/Virtualization/avmd"
-    },
-    {
-      "path": "packages/modules/Virtualization/encryptedstore"
-    },
-    {
-      "path": "packages/modules/Virtualization/libs/apexutil"
-    },
-    {
-      "path": "packages/modules/Virtualization/libs/apkverify"
-    },
-    {
-      "path": "packages/modules/Virtualization/libs/devicemapper"
-    },
-    {
-      "path": "packages/modules/Virtualization/microdroid_manager"
-    },
-    {
-      "path": "packages/modules/Virtualization/virtualizationmanager"
-    },
-    {
-      "path": "packages/modules/Virtualization/vm"
-    },
-    {
-      "path": "packages/modules/Virtualization/zipfuse"
-    },
-    {
-      "path": "system/keymint/derive"
-    },
-    {
-      "path": "system/keymint/hal"
-    },
-    {
-      "path": "system/security/diced"
-    },
-    {
-      "path": "system/security/keystore2"
-    },
-    {
-      "path": "system/security/keystore2/legacykeystore"
-    },
-    {
-      "path": "system/security/keystore2/selinux"
-    },
-    {
-      "path": "system/security/keystore2/src/crypto"
-    }
-  ]
-}
diff --git a/cargo_embargo.json b/cargo_embargo.json
deleted file mode 100644
index 0863453..0000000
--- a/cargo_embargo.json
+++ /dev/null
@@ -1,16 +0,0 @@
-{
-  "features": [
-    "default",
-    "full",
-    "visit",
-    "visit-mut",
-    "extra-traits"
-  ],
-  "package": {
-    "syn": {
-      "device_supported": false,
-      "host_first_multilib": true
-    }
-  },
-  "run_cargo": false
-}