pvm_exec: Set up Android logger

I might not had needed it since it's working, but this should have been
done anyway in the first place.

Bug: None
Test: See the log in logcat
Change-Id: Ib9df6356c21264304d16efb25ec917045ebd9237

compos/Android.bp

@@ -7,6 +7,7 @@ rust_binary {
     srcs: ["src/pvm_exec.rs"],
     rustlibs: [
         "compos_aidl_interface-rust",
+        "libandroid_logger",
         "libanyhow",
         "libbinder_rpc_unstable_bindgen",
         "libbinder_rs",

compos/src/pvm_exec.rs

@@ -166,6 +166,12 @@ fn parse_args() -> Result<Config> {
 }
 
 fn main() -> Result<()> {
+    let debuggable = env!("TARGET_BUILD_VARIANT") != "user";
+    let log_level = if debuggable { log::Level::Trace } else { log::Level::Info };
+    android_logger::init_once(
+        android_logger::Config::default().with_tag("pvm_exec").with_min_level(log_level),
+    );
+
     // 1. Parse the command line arguments for collect execution data.
     let Config { args, metadata, cid, debuggable } = parse_args()?;