Allow specifying sub-dir in sbox output

xsdc commands end up using the same output directory inside sbox
for reading and writing the output archive, resulting in including
a partial copy of the archive in itself.

This change allows that rule to specify a sub-directory for the inputs
leaving the output archive outside of it.

Used by https://r.android.com/2955427

Bug: b/322788229
Test: Ran a couple of builds and confirmed no cache misses from xsdc.
Also manually checked an archive and confirmed
abcence of partial self-copies.

Change-Id: If709b111458a83d58906d919c3d2a7787bcbe4ee
diff --git a/android/rule_builder.go b/android/rule_builder.go
index e8dbd48..85e29bd 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -1157,11 +1157,15 @@
 
 // OutputDir adds the output directory to the command line. This is only available when used with RuleBuilder.Sbox,
 // and will be the temporary output directory managed by sbox, not the final one.
-func (c *RuleBuilderCommand) OutputDir() *RuleBuilderCommand {
+func (c *RuleBuilderCommand) OutputDir(subPathComponents ...string) *RuleBuilderCommand {
 	if !c.rule.sbox {
 		panic("OutputDir only valid with Sbox")
 	}
-	return c.Text(sboxOutDir)
+	path := sboxOutDir
+	if len(subPathComponents) > 0 {
+		path = filepath.Join(append([]string{sboxOutDir}, subPathComponents...)...)
+	}
+	return c.Text(path)
 }
 
 // DepFile adds the specified depfile path to the paths returned by RuleBuilder.DepFiles and adds it to the command