* gnulib-tool.py (main) Accept options --conditional-dependencies,
--no-conditional-dependencies.
* pygnulib/GLModuleSystem.py (GLModuleTable.addConditional): Use
str(module), not module, as key. Fix logic bug.
(GLModuleTable.getCondition): Simplify.
(GLModuleTable.transitive_closure): Show a warning when there are
duplicate dependencies. Fix logic bug.
(GLModuleTable.transitive_closure_separately): Simplify.
(GLModuleTable.add_dummy): Ignore tests modules. Cope with multiple
lib_SOURCES augmentation lines. Cope with comments at the end of a
lib_SOURCES augmentation line. Add the dummy module at the end of the
modules list.
* pygnulib/GLTestDir.py (GLTestDir.execute): Remove the code that forces
the dummy module to the end of the list.
* pygnulib/GLEmiter.py (GLEmiter.autoconfSnippets): Add code to
terminate the shell functions. Add code for the dependencies from the
unconditional to the conditional modules. Don't emit AM_CONDITIONAL for
unconditional modules.