Copy SBOM files to directory dist/sbom instead of dist/.

There will be more SBOM files for unbundled APEXs/APks, so collect all in sbom/ for scilo ingestion later.

Bug: 266726655
Test: CIs
Test: lunch aosp_cf_x86_64_phone-userdebug && m dist
Change-Id: Iff4f1177df425095cef3c95c7bf4b85c62fa2e8d
diff --git a/core/main.mk b/core/main.mk
index a738dd9..df42baa 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -2194,7 +2194,7 @@
 	rm -rf $@
 	$(GEN_SBOM) --output_file $@ --metadata $(PRODUCT_OUT)/sbom-metadata.csv --product_out_dir=$(PRODUCT_OUT) --build_version $(BUILD_FINGERPRINT_FROM_FILE) --product_mfr="$(PRODUCT_MANUFACTURER)" --json
 
-$(call dist-for-goals,droid,$(PRODUCT_OUT)/sbom.spdx.json)
+$(call dist-for-goals,droid,$(PRODUCT_OUT)/sbom.spdx.json:sbom/sbom.spdx.json)
 else
 apps_only_sbom_files := $(sort $(patsubst %,%.spdx,$(apps_only_installed_files)))
 $(apps_only_sbom_files): $(PRODUCT_OUT)/sbom-metadata.csv $(GEN_SBOM)