This is slightly different to the original patch I posted. This adds
separate module target and dependency functions (rather than a single
bi-modal function).
libcpp/
* include/cpplib.h (struct cpp_options): Add modules to
dep-options.
* include/mkdeps.h (deps_add_module_target): Declare.
(deps_add_module_dep): Declare.
* mkdeps.c (class mkdeps): Add modules, module_name, cmi_name,
is_header_unit fields. Adjust cdtors.
(deps_add_module_target, deps_add_module_dep): New.
(make_write): Write module dependencies, if enabled.
db87f19ae3