Added -new_api_no_strip command line option

-new_api_no_strip will not strip references to classes that are not present in
the API description files being generated. This is needed to generate an API
description for the org.apache.http.legacy library that does not overlap the
Android API description.

Bug: 18027885
Test: cts/tests/signature/runSignatureTests.sh
Change-Id: I01ccd165e6d912873e92f44647f4df5e78531bdf
2 files changed