libbinder: include full error if cannot init

We've seen a few cases of the "Binder driver could not be opened" error
appearing in production, but in most of these contexts, we don't
actually have access to the full logs (we only have the tombstone).
However, all of the different errors that could happen (running out of
FDs, failure to mmap, etc..) would be logged previously. Now, the error
is kept, and it is included in the tombstone.

Bug: 197637414 (and many others)
Test: boot, binderLibTest
Test: manually verify error is printed (we don't have an existing test to put this in because
  ProcessState can only be initialized once):
    Binder driver '/dev/null' could not be opened. Terminating: Binder ioctl to obtain version failed: Inappropriate ioctl for device
Merged-In: I636f1c5bfa9c8932e3db3d84af46ce3b0f1e98bc
Change-Id: I636f1c5bfa9c8932e3db3d84af46ce3b0f1e98bc