java.security.spec: update classes in java.security.spec

Pulling upstream changes from OpenJDK version jdk8u60 for all classes
in java.security.spec

This commit contains cosmetic JavaDoc changes like use of @code in
place of <code> tags, use of a package-info.java in
place of a package.html file and new comments.

It remains to change MGF1ParameterSpec: it contains a small API
change so it will be updated in a following CL.

Change-Id: Ib36104b0bd3d68aa1471c9cc73d77fef8be7120c
Test: check-ojluni-files and make droid docs
Bug: 29631070
23 files changed