Revert "manifest: remove external/connectivity"

* The original commit message was misleading, this is a CAF repo
  and is needed to build libcnefeatureconfig for most recent qcom SoCs
* It no longer depends on libstlport

This reverts commit 2ff368fe.

Change-Id: I1690d32a76e1cbf8b847fe04a926de964fd8cb5a