Write dexpreopt.config again during the build

Writing $OUT/dexpreopt.config during build setup and then using
it during the build causes bad incremental builds if a cleanspec
removes $OUT/dexpreopt.config.  Create a rule in Soong to write
out a copy so that it is a normal build artifact.

Bug: 132379813
Test: m checkbuild
Change-Id: I7755a7f8c1d6561fc83022a7f4cf7e4a64e989c9

dexpreopt/dexpreopt_gen/dexpreopt_gen.go

@@ -78,7 +78,7 @@ func main() {
 
 	ctx := &pathContext{android.TestConfig(*outDir, nil)}
 
-	globalConfig, err := dexpreopt.LoadGlobalConfig(ctx, *globalConfigPath)
+	globalConfig, _, err := dexpreopt.LoadGlobalConfig(ctx, *globalConfigPath)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "error loading global config %q: %s\n", *globalConfigPath, err)
 		os.Exit(2)