Fixing build after bazelbuild-rules_cc update

This CL broke the build
https://r.android.com/3464086

The problem was missing 'cc_proto_library_bzl' library.

Added fake target to fake 'protobuf' module to fix it.

Bug: N/A
Change-Id: Id07fcad8d1d4d680d2c3a12cb7216b67c34c24ef