Wrap main function, to set up console before and shutdown after.

Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: Idf1f9d30a5118737134a31c65375cdc293ede117
diff --git a/vmbase/src/lib.rs b/vmbase/src/lib.rs
index 0901e04..90d6fc2 100644
--- a/vmbase/src/lib.rs
+++ b/vmbase/src/lib.rs
@@ -17,6 +17,7 @@
 #![no_std]
 
 pub mod console;
+mod entry;
 pub mod power;
 pub mod uart;