libbinder: disallow upgrade of explicit version

If we have explicitly set a version, we want to test that that version
is actually being used, and we don't want the other side of the
connection to decide to artificially upgrade the version.

Bug: 182938972
Test: binderRpcTest (w/ Cls to simulate versions added)
Change-Id: Id784672100c0445d5ea77c4fc3b063daa5efa0b0