Merge from origin/emacs-25

ca50981 Improve time zone documentation
c23c965 Prevent bootstrap autoload backup files
9344612 Disable multicolor fonts on OS X since they are not supported...
c41ce1c Capitalize “Universal Time” in documentation
10597c9 Don't use 'find-program'

diff --cc doc/emacs/cmdargs.texi
Simple merge

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

diff --cc etc/NEWS
Simple merge

diff --cc etc/PROBLEMS
Simple merge

diff --cc lisp/calendar/solar.el
Simple merge

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

diff --cc lisp/gnus/gnus-art.el
Simple merge

diff --cc lisp/vc/add-log.el
Simple merge

diff --cc src/editfns.c
Simple merge