Extract a library for common CompOS things

A small refactoring as a preliminary step to creating composd.

Create a Rust library for useful things shared by various
CompOS-related binaries. This initially includes the code to start the
VM and connect to CompOS, as well as various useful constants.

As part of extracting the start VM code I migrated to using logging
directly rather than writing to stdout/stderr for greater reusability,
as suggested by Victor.

Bug: 186126194
Test: Get odsign to run compos_verify_key, still works
Change-Id: I57b7ebcdd1a6cb604b5d739b8a8e028fd59e7b90
diff --git a/compos/src/compsvc_main.rs b/compos/src/compsvc_main.rs
index 46c8f8c..9855b53 100644
--- a/compos/src/compsvc_main.rs
+++ b/compos/src/compsvc_main.rs
@@ -16,16 +16,15 @@
 
 //! A tool to start a standalone compsvc server that serves over RPC binder.
 
-mod common;
 mod compilation;
 mod compos_key_service;
 mod compsvc;
 mod fsverity;
 mod signer;
 
-use crate::common::VSOCK_PORT;
 use anyhow::{bail, Result};
 use binder::unstable_api::AsNative;
+use compos_common::COMPOS_VSOCK_PORT;
 use log::debug;
 
 fn main() -> Result<()> {
@@ -40,7 +39,7 @@
     let retval = unsafe {
         binder_rpc_unstable_bindgen::RunRpcServer(
             service.as_native_mut() as *mut binder_rpc_unstable_bindgen::AIBinder,
-            VSOCK_PORT,
+            COMPOS_VSOCK_PORT,
         )
     };
     if retval {