Refactor the test harness for external repo tests (#1994)

- Use CTest labels to filter tests ("internal"/"external", "free"/"nonfree",
  and individual tool+project names) instead of defining `TESTS_RUN_NONFREE`
- Allow each external test to run independently in CTest
- Remove the unused no-op `fetch-test-deps.sh --only-internal` option

test/run-tests.sh

@@ -39,7 +39,6 @@ while [[ $# -gt 0 ]]; do
 			;;
 		--only-internal)
 			external=false
-			FETCH_TEST_DEPS="$FETCH_TEST_DEPS --only-internal"
 			;;
 		--only-external)
 			internal=false
@@ -109,35 +108,18 @@ fi
 
 # Test some significant external projects that use RGBDS
 # When adding new ones, don't forget to add them to the .gitignore!
-# When updating subprojects, change the commit being checked out, and set the `shallow-since`
-# to the day before, to reduce the amount of refs being transferred and thus speed up CI.
-
-test_downstream() { # owner repo make-target build-file build-hash
-	if ! pushd "$2"; then
-		echo >&2 'Please run `'"$FETCH_TEST_DEPS"'` before running the test suite'
-		return 1
-	fi
-	make clean $RGBDS_PATH
-	make -j4 "$3" $RGBDS_PATH
-	hash="$(sha1sum -b "$4" | head -c 40)"
-	if [ "$hash" != "$5" ]; then
-		echo >&2 'SHA-1 hash of '"$4"' did not match: '"$hash"
-		return 1
-	fi
-	popd
-}
 
 if "$nonfree"; then
-	test_downstream pret  pokecrystal      compare pokecrystal.gbc f4cd194bdee0d04ca4eac29e09b8e4e9d818c133
-	test_downstream pret  pokered          compare pokered.gbc     ea9bcae617fdf159b045185467ae58b2e4a48b9a
-	test_downstream zladx LADX-Disassembly default azle.gbc        d90ac17e9bf17b6c61624ad9f05447bdb5efc01a
+	./external/test.sh pokecrystal
+	./external/test.sh pokered
+	./external/test.sh ladx
 fi
-test_downstream AntonioND ucity   all      ucity.gbc 5f026649611c9606ce0bf70dc1552e054e7df5bc
-test_downstream pinobatch libbet  all      libbet.gb f117089aa056600e2d404bbcbac96b016fc64611
-test_downstream LIJI32    SameBoy bootroms build/bin/BootROMs/cgb_boot.bin 113903775a9d34b798c2f8076672da6626815a91
+./external/test.sh ucity
+./external/test.sh libbet
+./external/test.sh sameboy
 # gb-starter kit fails with any `make` on Windows: https://codeberg.org/ISSOtm/gb-starter-kit/issues/1
 # gb-starter-kit fails with macOS/BSD `make`: https://codeberg.org/ISSOtm/gb-starter-kit/issues/29
 case "${osname%%-*}" in
 	windows | macos | *bsd) ;;
-	*) test_downstream ISSOtm gb-starter-kit all bin/boilerplate.gb b4f130169ba73284e0d0e71b53e7baa4eca2f7fe;;
+	*) ./external/test.sh gb-starter-kit
 esac