Enable restat for sbox rules

Add support to sbox for only writing output files if they are changed
to support enabling restat.  Move the clearing of the output directory
into sbox, and when write if changed is enabled delete obsolete output
files without deleting output files that will be replaced.

Enable restat for local metalava rules.  Restat for metalava rules
run remotely is still blocked on b/183630617.

Bug: 222095735
Test: TestRuleBuilder_Build
Test: m SystemUI
Change-Id: If8fc47e711f4a6f43947ab69f17cccc8ba6ae61a

java/droidstubs.go

@@ -433,6 +433,10 @@ func (d *Droidstubs) apiLevelsAnnotationsFlags(ctx android.ModuleContext, cmd *a
 	}
 }
 
+func metalavaUseRbe(ctx android.ModuleContext) bool {
+	return ctx.Config().UseRBE() && ctx.Config().IsEnvTrue("RBE_METALAVA")
+}
+
 func metalavaCmd(ctx android.ModuleContext, rule *android.RuleBuilder, javaVersion javaVersion, srcs android.Paths,
 	srcJarList android.Path, bootclasspath, classpath classpath, homeDir android.WritablePath) *android.RuleBuilderCommand {
 	rule.Command().Text("rm -rf").Flag(homeDir.String())
@@ -441,7 +445,7 @@ func metalavaCmd(ctx android.ModuleContext, rule *android.RuleBuilder, javaVersi
 	cmd := rule.Command()
 	cmd.FlagWithArg("ANDROID_PREFS_ROOT=", homeDir.String())
 
-	if ctx.Config().UseRBE() && ctx.Config().IsEnvTrue("RBE_METALAVA") {
+	if metalavaUseRbe(ctx) {
 		rule.Remoteable(android.RemoteRuleSupports{RBE: true})
 		execStrategy := ctx.Config().GetenvWithDefault("RBE_METALAVA_EXEC_STRATEGY", remoteexec.LocalExecStrategy)
 		labels := map[string]string{"type": "tool", "name": "metalava"}
@@ -665,7 +669,9 @@ func (d *Droidstubs) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 	}
 
 	// TODO(b/183630617): rewrapper doesn't support restat rules
-	// rule.Restat()
+	if !metalavaUseRbe(ctx) {
+		rule.Restat()
+	}
 
 	zipSyncCleanupCmd(rule, srcJarDir)