code-style for pledge: check the return code -1, not < 0

this is the proper idiom

dmenu.c

@@ -750,7 +750,7 @@ main(int argc, char *argv[])
 	lrpad = drw->fonts->h;
 
 #ifdef __OpenBSD__
-	if (pledge("stdio rpath", NULL) < 0)
+	if (pledge("stdio rpath", NULL) == -1)
 		die("pledge");
 #endif