Revert "manage: For isfloating/oldstate check/set, ensure trans client actually exists"

This reverts commit bece862a0fc4fc18ef9065b18cd28e2032d0d975.

It caused a regression, for example:
https://lists.suckless.org/hackers/2203/18220.html

Ref.
https://git.suckless.org/dwm/commit/a4771de5ba54a38b062a7d748635f21c141b5c7e.html

dwm.c

@@ -2439,7 +2439,7 @@ manage(Window w, XWindowAttributes *wa)
 	#endif // MAXIMIZE_PATCH / EXRESIZE_PATCH
 
 	if (!c->isfloating)
-		c->isfloating = c->oldstate = t || c->isfixed;
+		c->isfloating = c->oldstate = trans != None || c->isfixed;
 	if (c->isfloating) {
 		XRaiseWindow(dpy, c->win);
 		XSetWindowBorder(dpy, w, scheme[SchemeNorm][ColFloat].pixel);