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/statslog_virtualization/Android.bp b/libs/statslog_virtualization/Android.bp
index 51a51a3..a702ea1 100644
--- a/libs/statslog_virtualization/Android.bp
+++ b/libs/statslog_virtualization/Android.bp
@@ -27,21 +27,28 @@
     ],
 }
 
+rust_defaults {
+    name: "libstatslog_virtualization_rust_defaults",
+    edition: "2021",
+    rustlibs: [
+        "libstatspull_bindgen",
+    ],
+    apex_available: [
+        "com.android.virt",
+    ],
+}
+
 rust_library {
     name: "libstatslog_virtualization_rust_header",
+    defaults: ["libstatslog_virtualization_rust_defaults"],
     crate_name: "statslog_virtualization_rust_header",
     srcs: [
         "statslog_header_wrapper.rs",
         ":statslog_virtualization_header.rs",
     ],
     rustlibs: [
-        "libstatspull_bindgen",
         "libthiserror",
     ],
-    apex_available: [
-        "com.android.virt",
-    ],
-
 }
 
 genrule {
@@ -55,6 +62,7 @@
 
 rust_library {
     name: "libstatslog_virtualization_rust",
+    defaults: ["libstatslog_virtualization_rust_defaults"],
     crate_name: "statslog_virtualization_rust",
     srcs: [
         "statslog_wrapper.rs",
@@ -62,10 +70,5 @@
     ],
     rustlibs: [
         "libstatslog_virtualization_rust_header",
-        "libstatspull_bindgen",
     ],
-    apex_available: [
-        "com.android.virt",
-    ],
-
 }