include: avoid "deleted .am file" problem

include: avoid "deleted .am file" problem

* automake.in (handle_configure): When processing `configure.am',
also expand `HAVE-MAKEFILE-IN-DEPS' to a boolean telling whether
`MAKEFILE-IN-DEPS' is empty or not.
* lib/am/configure.am [?HAVE-MAKEFILE-IN-DEPS?]
(%MAKEFILE-IN-DEPS%): New target without dependencies, to
avoid the "deleted .am file" problem.  Emit this only when
`?HAVE-MAKEFILE-IN-DEPS?' is true, to avoid generating an
"empty" dependency declaration.
* tests/deleted-am.test: Make grepping of error message stricter.
* tests/dist-missing-am.test: Likewise.
* tests/remake-deleted-am.test: New test.
* tests/remake-deleted-am-2.test: Likewise.
* tests/remake-deleted-am-subdir.test: Likewise.
* tests/remake-renamed-am.test: Likewise.
* tests/makefile-deps.test: Likewise.
* tests/Makefile.am (TESTS): Add the new tests.
* NEWS: Update.

Fixes automake bug#9768.

Report by Peter Johansson.

See also commit `Release-1-10-40-gd0ebf71', which fixed a similar
problem for .m4 files included by configure.ac.