build_sources = $(foreach module,$(build_modules),$($(module)_sources))
build_headers = $(foreach module,$(build_modules),$($(module)_headers))
build_links = $(notdir $(build_sources))
build_sources = $(foreach module,$(build_modules),$($(module)_sources))
build_headers = $(foreach module,$(build_modules),$($(module)_headers))
build_links = $(notdir $(build_sources))