Add test/vts-testcase/* to root.bp

Test: make vts
Change-Id: I863d30344c67e11429009be5ea99bc4e592bcb15
diff --git a/root.bp b/root.bp
index 58f4f10..a1b1f6b 100644
--- a/root.bp
+++ b/root.bp
@@ -31,5 +31,6 @@
     "system/*",
     "system/tools/*",
     "test/vts",
+    "test/vts-testcase/*",
     "vendor/*/*",
 ]