makefile: remove gcov files and core dumps

Makefile.in

@@ -70,7 +70,8 @@ distclean : clean
 	-rm -f Makefile config.h config.log
 
 clean :
-	-rm -f *.o *.s chronyc chronyd core *~
+	-rm -f *.o *.s chronyc chronyd core.* *~
+	-rm -f *.gcda *.gcno
 	-rm -rf .deps
 	-rm -rf *.dSYM
 

test/unit/Makefile.in

@@ -30,7 +30,7 @@ check: $(TESTS)
 	exit $$ret
 
 clean:
-	rm -f *.o $(TESTS)
+	rm -f *.o *.gcda *.gcno core.* $(TESTS)
 	rm -rf .deps
 
 distclean: clean