* lib/Automake/Variable.pm (vardef, rvardef, set_seen): New functions.

* lib/Automake/Variable.pm (vardef, rvardef, set_seen): New functions.
(variable_defined, examine_variable): Remove.
(%_ac_macro_for_var): Add an entry for ALLOCA.
(require_variables): Use vardef instead of variable_defined.
Do not use _cvar.
* automake.in (generate_makefile): Do not push $(SOURCE) into
@sources.  Use define_pretty_variable to define SOURCES.
(handle_LIBOBJS, handle_ALLOCA): Use require_variables_for_variable
to require LIBOBJS, LTLIBOBJS and ALLOCA.
(handle_programs, handle_ltlibraries): Do not define an empty
_DEPENDENCIES or _LDFLAGS variable when none is defined.
(define_configure_variable): Do not check whether the variable
already exists (it's Automake::Variable::define's job).
(require_build_directory): Likewise, do not check
the existence of am__dirstamp.
(generate_makefile, handle_options, handle_languages)
(check_libobjs_sources, handle_single_transform_list)
(traverse_variable_recursively_worker, handle_source_transform)
(handle_lib_objects, handle_LIBOBJS, handle_compile)
(handle_libtool, handle_programs, handle_libraries)
(handle_ltlibraries, check_typos, handle_texinfo_helper)
(handle_man_pages, handle_tags, handle_dist, handle_subdirs)
(scan_aclocal_m4, handle_gettext, handle_footer, handle_install)
(handle_all, do_check_merge_target, handle_clean, lang_c_finish)
(handle_tests, lang_yacc_target_hook, define_pretty_variable)
(define_compiler_variable, define_linker_variable)
(make_paragraphs, am_primary_prefixes, am_install_var): Adjust to
call var, vardef, or set_seen, instead of variable_defined.  Use
set_seen only for variables which are actually checked by
check_typos.
* tests/target.test: Delete.
* tests/alloca.test, tests/alloca2.test: New files.
* tests/libobj3.test: Check error message.
* tests/distcom4.test: Make sure configure is in DIST_COMMON.
This replace confdist.test.
* tests/Makefile.am (TESTS, XFAIL_TESTS): Remove target.test.
(TESTS): Add alloca.test and alloca2.test.  Remove confdist.test.