rust: syn: enable support in kbuild

With all the new files in place and ready from the new crate, enable
the support for it in the build system.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Tested-by: Gary Guo <gary@garyguo.net>
Tested-by: Jesung Yang <y.j3ms.n@gmail.com>
Link: https://patch.msgid.link/20251124151837.2184382-20-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

scripts/generate_rust_analyzer.py

@@ -100,6 +100,13 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs, core_edit
         cfg=crates_cfgs["quote"],
     )
 
+    append_crate(
+        "syn",
+        srctree / "rust" / "syn" / "lib.rs",
+        ["proc_macro", "proc_macro2", "quote"],
+        cfg=crates_cfgs["syn"],
+    )
+
     append_crate(
         "macros",
         srctree / "rust" / "macros" / "lib.rs",