It conflicts with a definition subr-x.el

(cherry picked from SLIME commit
0b258267)

Conflicts:
	ChangeLog
	contrib/slime-enclosing-context.el
	contrib/slime-package-fu.el
	contrib/slime-references.el
	contrib/slime-repl.el
	contrib/sly-fontifying-fu.el
	lib/sly-tests.el
	slime.el