Binder linkage no longer depends on JNI objrefs as persistent tokens

There are two areas that have changed to eliminate the assumption that
local jobject references are both canonical and persistent:

1. JavaBBinderHolder no longer holds onto and reuses it parent object
reference per se.  Since the underlying JavaBBinder object holds a
real global ref, this was redundant anyway.  Now, for purposes of its
transient need to perform JNI operations, it simply uses the current
jobject ref(s) passed during method invocation, and no longer attempts
to hold these refs beyond the scope of a single invocation.

2. Binder obituaries no longer assume that a jobject reference to a
recipient will always compare == as a 32-bit value with any future
reference to the same object.  The implementation now asks Dalvik
whether object references match.

Bug 2090115

Change-Id: If62edd554d0a9fbb2d2977b0cbf8ad7cc8e2e68d