Switch native bridge libc to LLVM prebuilt unwinder

The guest libc.so needs to have its unwinder symbols exported, so use
libunwind-exported.a rather than libunwind.a (which has most of its
symbols hidden and should eventually hide all of them). This matches
the ordinary libc.so.

Bug: http://b/153025717
Test: run ndk_translation bionic unit tests
Change-Id: Ia27a9610b9d21180e9f2c10c2de65b3787d2f4e8
1 file changed