Reformat some testing rules for clarity

tests/Makefile

@@ -56,7 +56,9 @@ all: ${TESTS} run-all
 
 run-all: ${TESTS}
 	@for test in ${TESTS}; do \
-		${MAKE} -s -f ${top_dir}/testing/makefiles/testcase.mk -C $${test} testcase=$${test} run || ERROR=$$?; \
+		${MAKE} -s -f ${top_dir}/testing/makefiles/testcase.mk \
+			-C $${test} \
+			testcase=$${test} run || ERROR=$$?; \
 	done; \
 	if [ -n $${ERROR} ]; then exit $${ERROR}; fi
 
@@ -67,7 +69,9 @@ cmake-clean:
 
 clean: cmake-clean
 	@for test in ${TESTS}; do \
-		${MAKE} -s -f ${top_dir}/testing/makefiles/testcase.mk -C $${test} testcase=$${test} clean; \
+		${MAKE} -s -f ${top_dir}/testing/makefiles/testcase.mk \
+			-C $${test} \
+			testcase=$${test} clean; \
 	done
 	rm -rf "${build_dir}"/*