Merge from origin/emacs-25

80128a7 Fix stability confusion in sort-tests
1e4aa42 Avoid describe-key error with lambdas
a05fb21 * lisp/emacs-lisp/package.el (package-install-selected-packag...
f501116 Sync with gnulib
c4963f9 Fix doc for Universal Time

diff --cc doc/lispref/os.texi
Simple merge

diff --cc etc/NEWS
Simple merge

diff --cc lisp/emacs-lisp/package.el
Simple merge

diff --cc test/lisp/sort-tests.el
Simple merge