prng_seeder is a bootstrap process in microdroid

It is started very early before linker namespaces are configured, thus
making it a bootstrap process. Also, it is built with `prefer_rlib:
true` so that we don't spend time for dynamically linking the dylibs.

Bug: 263398430
Test: watch boottime benchmark
Change-Id: I5193d0d36958de5b6d6dfa8584212f82edb727bc
diff --git a/prng_seeder/Android.bp b/prng_seeder/Android.bp
index 5759731..292535a 100644
--- a/prng_seeder/Android.bp
+++ b/prng_seeder/Android.bp
@@ -31,10 +31,9 @@
     ],
 }
 
-rust_binary {
-    name: "prng_seeder",
+rust_defaults {
+    name: "prng_seeder_defaults",
     edition: "2021",
-    srcs: ["src/main.rs"],
     rustlibs: [
         "libanyhow",
         "libbssl_ffi",
@@ -48,3 +47,19 @@
 
     init_rc: ["prng_seeder.rc"],
 }
+
+rust_binary {
+    name: "prng_seeder",
+    defaults: ["prng_seeder_defaults"],
+    srcs: ["src/main.rs"],
+}
+
+rust_binary {
+    name: "prng_seeder_microdroid",
+    defaults: ["prng_seeder_defaults"],
+    srcs: ["src/main.rs"],
+    stem: "prng_seeder",
+    bootstrap: true,
+    installable: false,
+    prefer_rlib: true,
+}