Merge from origin/emacs-26

037970f Document insert-image-file's return value (Bug#32978)
598b45a Autoload cua-toggle-rectangle-mark (Bug#34947)
95bd56d Tell xclip not to expect job-control under eshell (Bug#35257)
9997bbb ; * src/emacs.c: Fix typo in comment (Bug#35320).
a4ad7be Fix off-by-one-link error in image--set-property

diff --cc lisp/emulation/cua-base.el
Simple merge

diff --cc lisp/eshell/esh-proc.el
Simple merge

diff --cc lisp/image-file.el
Simple merge

diff --cc lisp/image.el
Simple merge

diff --cc src/emacs.c
Simple merge