statically link adb and fastboot against libc++

libc++.so is not widely available on the host, so we compile against
one built as part of the platform.  This causes problems for adb and
fastboot, which are distributed through a number of channels - the
sdk, distro packages, downloaded from the build server, or manually
copied.  Instead of forcing all users to handle libc++.so too,
statically link against libc++.

Change-Id: I51b75258653a23558c8b598802005f6c1166a439
diff --git a/Android.mk b/Android.mk
index 3733ae3..5bba23e 100644
--- a/Android.mk
+++ b/Android.mk
@@ -161,6 +161,13 @@
     LOCAL_STATIC_LIBRARIES += libcutils
 endif
 
+LOCAL_CXX_STL := libc++_static
+
+# Don't add anything here, we don't want additional shared dependencies
+# on the host adb tool, and shared libraries that link against libc++
+# will violate ODR
+LOCAL_SHARED_LIBRARIES :=
+
 include $(BUILD_HOST_EXECUTABLE)
 
 $(call dist-for-goals,dist_files sdk,$(LOCAL_BUILT_MODULE))