Fix defaults of BaseCompilerProperties

* Edition and Deny_warnings should not be set when
  constructing a BaseCompilerProperties, or the
  initialized values will reject values inherited from rust_defaults.
* Use getEdition and getDenyWarnings to retrieve those properties
  with defaults from config.

Bug: 141699953
Test: mm in rust projects
Change-Id: Id1ae357caeaf656cd33732bf4e54920e206f4ead

rust/config/global.go

@@ -17,8 +17,6 @@ package config
 import (
 	"strings"
 
-	"github.com/google/blueprint/proptools"
-
 	"android/soong/android"
 	_ "android/soong/cc/config"
 )
@@ -35,7 +33,7 @@ var (
 		"libtest",
 	}
 
-	DefaultDenyWarnings = proptools.BoolPtr(true)
+	DefaultDenyWarnings = true
 
 	GlobalRustFlags = []string{
 		"--remap-path-prefix $$(pwd)=",