Convert libcore native code to Android.bp

See build/soong/README.md for more information.

Reapplies Ibf27f08e22f544582271bbe04af17cff278bd996 with fix for
CtsLibcoreTestCases.

Test: m -j checkbuild
Test: libjavacore-unit-tests
Test: cts-tradefed run cts -m CtsLibcoreTestCases -t dalvik.system.JniTest
Change-Id: Ia4d7eb3f8ba4b97428606bb60df34dc1256eeaa1
diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..2230ac7
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,3 @@
+build = [
+    "NativeCode.bp",
+]