For PR automake/428:

For PR automake/428:
Support for conditionally defined -hook and -local rules.
* automake.in (user_phony_rule): New function.
(handle_dist, handle_install, handle_all, do_check_merge_target,
handle_factored_dependencies): Use user_phony_rule before
adding a user -hook or -local rule as a dependency to ensure
it is always defined an phony.
* tests/cond37.test, tests/condhook.test: New files.
* tests/Makefile.am (TESTS): Add them.
Report from Simon Josefsson and Nik A. Melchior.