Build connectivity JNI against libc++_static

Instead of including the whole libc++ library by linking it dynamically,
use the static version so that unused symbols can be stripped.

This allows reducing the APEX size by 1MB (3.7MB -> 2.7MB), as otherwise
libc++ is included twice for 32 and 64 bit variants.

Original change (project moved):
Ia66d795cf23d6f45997278300c103976433f7c5c

Bug: 171540887
Test: Device boots and has connectivity, size reduced

Merged-In: I3c2563d4ae4e3715d0c6270344ba8f7ef067872f
Change-Id: Ie1c5b2ea274238a226ad2d827148439fd5758bb5
diff --git a/framework/Android.bp b/framework/Android.bp
index 2a03b73..4fa9ccb 100644
--- a/framework/Android.bp
+++ b/framework/Android.bp
@@ -137,6 +137,7 @@
         "jni/onload.cpp",
     ],
     shared_libs: ["libandroid"],
+    stl: "libc++_static",
     apex_available: [
         "//apex_available:platform",
         "com.android.tethering",