libservice-connectivity - dynamically link c++ - saves 600 kB

Before in /apex/com.android.tethering/lib:
  -rw-r--r-- 1 system system 749980 1969-12-31 16:00 libservice-connectivity.so
After:
  -rw-r--r-- 1 system system 150748 1969-12-31 16:00 libservice-connectivity.so

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I6892d81ca597d27cc1a85180f7ffa39f2b3de1be
diff --git a/service/Android.bp b/service/Android.bp
index 2e997c5..a3a2825 100644
--- a/service/Android.bp
+++ b/service/Android.bp
@@ -61,7 +61,6 @@
         "jni/com_android_server_TestNetworkService.cpp",
         "jni/onload.cpp",
     ],
-    stl: "libc++_static",
     header_libs: [
         "bpf_connectivity_headers",
         "libbase_headers",