The files man/*.1 are included in the tarballs. By the GNU Coding Standards
<https://www.gnu.org/prep/standards/html_node/Makefile-Basics.html>
they should be generated in the source directory.

But this is not what happens:

$ ./configure; make -k maintainer-clean
$ ./bootstrap
$ mkdir bb
$ cd bb
$ ../configure
$ make
$ ls -l ../man/*.1
ls: cannot access '../man/*.1': No such file or directory
$ ls -l man/*.1
-rw-rw-r-- 1 bruno bruno 2245 21. Jul 21:12 man/cmp.1
-rw-rw-r-- 1 bruno bruno 6469 21. Jul 21:12 man/diff.1
-rw-rw-r-- 1 bruno bruno 2858 21. Jul 21:12 man/diff3.1
-rw-rw-r-- 1 bruno bruno 2869 21. Jul 21:12 man/sdiff.1

This patch fixes it.

With it, the result is:

$ ls -l ../man/*.1
-rw-rw-r-- 1 bruno bruno 2245 21. Jul 21:16 ../man/cmp.1
-rw-rw-r-- 1 bruno bruno 6469 21. Jul 21:16 ../man/diff.1
-rw-rw-r-- 1 bruno bruno 2858 21. Jul 21:16 ../man/diff3.1
-rw-rw-r-- 1 bruno bruno 2869 21. Jul 21:16 ../man/sdiff.1
$ ls -l man/*.1
ls: cannot access 'man/*.1': No such file or directory