soong: fix absolute path check in validatePath

breaks support for absolute out dir

Add: thx to
https://github.com/LineageOS/android_build_soong/commit/883519c94711de4e8b4e3368231451604a500d0b

For the solution to check for i != initialEmpty

Change-Id: Ibb17eb0601a079f0f6c3f452aa7cbc34cd191e6d
diff --git a/android/paths.go b/android/paths.go
index edc0700..6f8f7f2 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -1970,7 +1970,7 @@
 		}
 
 		path := filepath.Clean(path)
-		if path == ".." || strings.HasPrefix(path, "../") || strings.HasPrefix(path, "/") {
+		if path == ".." || strings.HasPrefix(path, "../") || i != initialEmpty && strings.HasPrefix(path, "/") {
 			return "", fmt.Errorf("Path is outside directory: %s", path)
 		}