selftests: use printf instead of echo -ne

Rather than trying to guess which implementation of "echo" to run with
support for "-ne" options, use "printf" instead of "echo -ne". It
handles escape characters as a standard feature and it is widespread
among modern shells.

Reported-by: "kernelci.org bot" <[e-mail]>
Suggested-by: David Laight <[e-mail]>
Fixes: 3297a4df805d ("kselftests: Enable the echo command to print newlines in Makefile")
Fixes: 79c16b1120fe ("selftests: find echo binary to use -ne options")
Signed-off-by: Guillaume Tucker <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/Makefile

···
 	@# While building kselftest-list.text skip also non-existent TARGET dirs:
 	@# they could be the result of a build failure and should NOT be
 	@# included in the generated runlist.
-	ECHO=`which echo`; \
 	for TARGET in $(TARGETS); do \
 		BUILD_TARGET=$$BUILD/$$TARGET;	\
-		[ ! -d $(INSTALL_PATH)/$$TARGET ] && $$ECHO "Skipping non-existent dir: $$TARGET" && continue; \
-		$$ECHO -ne "Emit Tests for $$TARGET\n"; \
+		[ ! -d $(INSTALL_PATH)/$$TARGET ] && printf "Skipping non-existent dir: $$TARGET\n" && continue; \
+		printf "Emit Tests for $$TARGET\n"; \
 		$(MAKE) -s --no-print-directory OUTPUT=$$BUILD_TARGET COLLECTION=$$TARGET \
 			-C $$TARGET emit_tests >> $(TEST_LIST); \
 	done;