build: the parent make knows what the daemon is built from

../strans listed no prerequisites, so once the file existed make held it
up to date whatever changed under it: touch strans.c, run
make -C tests check-live, and it planned no compile at all and smoked a
stale daemon.  The sibling rule for the GTK module answered it by naming
three of its sources, which is the parent Makefile's list copied and
already short of gtk/Makefile.  Neither list is needed -- ask the parent.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/Makefile

@@ -89,7 +89,8 @@ gtk_live_test: gtk_live_test.c $(LIVESRC) ../ipc.c ../ipc.h
 		$(LDFLAGS) -o $@ gtk_live_test.c live.c ../ipc.c $(GTK_LIBS) \
 		-pthread $(LDLIBS)
 
-../gtk/im-strans.so: ../gtk/main.c ../ipc.c ../ipc.h
+# The parent make knows what these are built from; always ask it.
+../gtk/im-strans.so:
 	$(MAKE) -C ../gtk
 
 ../strans:
@@ -145,4 +146,5 @@ unit_%.o: ../%.c ../dat.h ../fn.h ../ipc.h
 clean:
 	rm -f $(OBJS) $(PROG) $(STRESS) $(LIVE)
 
-.PHONY: all check check-live check-stress test clean
+.PHONY: all check check-live check-stress test clean \
+	../strans ../gtk/im-strans.so