gn2bp: Add Android.extras.bp support

Test: TH
Change-Id: I66bbbb17446ea1f87e07b3d63d2c4e1ffa9d1a51
diff --git a/tools/gn2bp/Android.bp.swp b/tools/gn2bp/Android.bp.swp
index 93443f5..b96ed98 100644
--- a/tools/gn2bp/Android.bp.swp
+++ b/tools/gn2bp/Android.bp.swp
@@ -14,6 +14,8 @@
 //
 // This file is automatically generated by gen_android_bp. Do not edit.
 
+build = ["Android.extras.bp"]
+
 // GN: PACKAGE
 package {
     default_applicable_licenses: [