Handle prebuilt vs source selection in bp2build

Test: enable mainline modules build from prebuilts and build
Bug: 300640274
Change-Id: Ib1d6bbca7e0ab459515d3cf6378741e8368e7327
diff --git a/android/allowlists/allowlists.go b/android/allowlists/allowlists.go
index 5b77ba9..9dc5878 100644
--- a/android/allowlists/allowlists.go
+++ b/android/allowlists/allowlists.go
@@ -340,6 +340,7 @@
 		"prebuilts/clang/host/linux-x86":                   Bp2BuildDefaultTrueRecursively,
 		"prebuilts/gradle-plugin":                          Bp2BuildDefaultTrueRecursively,
 		"prebuilts/runtime/mainline/platform/sdk":          Bp2BuildDefaultTrueRecursively,
+		"prebuilts/module_sdk":                             Bp2BuildDefaultTrueRecursively,
 		"prebuilts/sdk":                                    Bp2BuildDefaultTrue,
 		"prebuilts/sdk/current/androidx":                   Bp2BuildDefaultTrue,
 		"prebuilts/sdk/current/androidx-legacy":            Bp2BuildDefaultTrue,