Update prebuilt signapk to #2612281 aosp-master-linux-aosp_x86_64-eng.

The Darwin conscrypt_openjdk_jni shared library is from
aosp-master-mac-sdk #2612281 build.

This update rolls up the following major changes from
build/tools/signapk:
* APK Signature Scheme v2 signatures are generated unless disabled via
  --disable-v2 command-line switch.
* Use Jan 1 2009 as timestamp in APKs.

Bug: 25794543
Bug: 26864066
Change-Id: Iaec6de13725d045a488aaac89fa9b32e8cc82bb9
3 files changed