Switch from using base64 BIOs to encoding funcs.

The OpenSSL base64 BIO is going away in BoringSSL. This change switches
to using the explicit base64 functions which are availible in both
OpenSSL and BoringSSL. The BoringSSL helper functions (i.e. for
calculating the size of the base64 encoding) are wrapped in #ifdefs so
that this change isn't coupled with the switch to BoringSSL. Once that
switch is complete, the #ifdefs can be removed.

Bug: 17409664
Change-Id: I42bac3bc93a1fb39feed39a8917d8e38d97629d3
Signed-off-by: Adam Langley <agl@google.com>
LibNativeBridge: Add testing

Change PreInitializeNativeBridge to have a different path for
the host to allow testing. Add a test (needs root privileges).

Add a test for NeedsNativeBridge.

Change error reporting to use strerror.

Change-Id: Id2d488f0484ff8b0438863b48ef43770e784505f
Don't manually link stlport.

Change-Id: I60d2bc868fb9052f120103e9675046ef54f510d0
Merge "Don't manually link stlport."
Merge "LibNativeBridge: Add testing"
Merge "Switch from using base64 BIOs to encoding funcs."