NVIDIA binary blobs are assuming that __cache_clear, _Unwind_Backtrace,
and _Unwind_GetIP are all in some library that they link, but now we've
cleaned up this leakage, they're no longer getting it. Deliberately leak
the symbols from libc.so until we get new blobs.
Bug: http://b/20065774
Change-Id: I92ef07b2bce8d1ad719bf40dab41d745cd6904d4
This used to be handled by -fvisibility=hidden on libc_cxa, but that
was broken by the resolution of https://llvm.org/PR22419 (introduced
to Android in today's clang update).
Now we just use a version script that prevents these from being
re-exported from our shared libraries.
Change-Id: Ib290e1d0d7426e09ad17a91178162fff6dbdcfa9