Migrate to Rust 2021 edition

I only wanted this in one place, but thought we might as well do it
all in one go.

In a couple of places I added an explicit edition instead of using the
default (whatever that is).

See https://doc.rust-lang.org/edition-guide/rust-2021/index.html.

Test: find . -name "Android.bp" -type f|xargs grep edition | grep -v 2021
Test: atest ComposHostTestCases MicrodroidHostTestCases
Change-Id: I4de050078b303cc5614d230e0d36d5454d60a807
diff --git a/libs/avb_bindgen/Android.bp b/libs/avb_bindgen/Android.bp
index 6dc16e8..80b96a6 100644
--- a/libs/avb_bindgen/Android.bp
+++ b/libs/avb_bindgen/Android.bp
@@ -7,6 +7,7 @@
     host_supported: true,
     wrapper_src: "bindgen/avb.h",
     crate_name: "avb_bindgen",
+    edition: "2021",
     visibility: ["//packages/modules/Virtualization:__subpackages__"],
     source_stem: "bindings",
     bindgen_flags: [
@@ -26,6 +27,7 @@
     name: "libavb_bindgen_test",
     srcs: [":libavb_bindgen"],
     crate_name: "avb_bindgen_test",
+    edition: "2021",
     test_suites: ["general-tests"],
     auto_gen_config: true,
     clippy_lints: "none",