Check for more ‘find’ failures and port ‘find’

Check for more ‘find’ failures and port ‘find’

* Makefile.in (install-eln), configure.ac (emacs_cv_find_delete):
* make-dist: Use ‘find ... -exec CMD {} +’ rather than ‘find
... -exec CMD {} \;’ so that if CMD fails, ‘find’ fails too.
* Makefile.in (install-eln): Port to ‘find’ implementations that
behave differently from GNU ‘find’ when given an argument
that contains ‘{}’ within a longer string.  POSIX allows
this behavior.

(cherry picked from commit 7cda30602fcaeecd0072d980a99156812fc7f086)