Revert "Sandbox soong_build by changing to root directory"

This reverts commit 05c25ccb4a.

Reason for revert: broke absolute OUT_DIR
Bug: 146437378

Change-Id: I523ed79d40e1c1ef040212ba794a7a084abea75d

android/package_ctx.go

@@ -19,6 +19,7 @@ import (
 	"strings"
 
 	"github.com/google/blueprint"
+	"github.com/google/blueprint/pathtools"
 )
 
 // PackageContext is a wrapper for blueprint.PackageContext that adds
@@ -59,6 +60,10 @@ func (e *configErrorWrapper) AddNinjaFileDeps(deps ...string) {
 	e.pctx.AddNinjaFileDeps(deps...)
 }
 
+func (e *configErrorWrapper) Fs() pathtools.FileSystem {
+	return nil
+}
+
 type PackageVarContext interface {
 	PathContext
 	errorfContext