Package bionic static libraries in the NDK.

Test: build/soong/scripts/build-ndk-prebuilts.sh
Bug: https://github.com/android-ndk/ndk/issues/272
Change-Id: Ibb21d799fdcf230ed45db0b809e20dd86d2d8e52
diff --git a/libdl/Android.bp b/libdl/Android.bp
index 3889bdb..0603d06 100644
--- a/libdl/Android.bp
+++ b/libdl/Android.bp
@@ -25,6 +25,7 @@
 
 cc_library {
     name: "libdl",
+    static_ndk_lib: true,
 
     defaults: ["linux_bionic_supported"],