Remove abi/cpp from the manifest

libgabi++ from abi/cpp was only useful with stlport and libstdc++,
neither of which is used in the platform any more.  The NDK has its own
copy of libgabi++, so remove the platform version.

Change-Id: I3c97a5e49c8b0e9d1269567e0c16da8b5df604aa
(cherry picked from commit aa1c5ac067a8ae8050aeb0ad0befdfbfbdddf9ea)