spraycan: fix cvar not being updated properly

GetCVar returns a per-player copy of the requested cvar, which is only
used to have separate values for each player - changes are propagated To
it, but not From it.
writing to this cvar is only useful if you know what the actual new
value is going to be & want the cvar to update Immediately.
(in this case, the cvar needs to be updated before A_SetHelpText so the
 displayed spray name is correct)

FindCVar returns the actual cvar for the local player. changes to this
cvar Are propagated to other clients.

zscript/spraycan.zs

@@ -322,8 +322,12 @@ class SnekTechSprayer : HDWeapon
         int newIndex = (currentIndex + 1) % patternList.size();
 
         // Set the new CVar.
-        CVar.GetCVar("snektech_spraypattern", owner.player).SetString(patternList[newIndex]);
-        currentPattern = CVar.GetCVar("snektech_spraypattern", owner.player).GetString();
+        currentPattern = patternList[newIndex];
+        // first, update the Actual cvar
+        if (owner.PlayerNumber() == consoleplayer)
+           CVar.FindCVar("snektech_spraypattern").SetString(currentPattern);
+        // then update the per-player copy so the help text is correct
+        CVar.GetCVar("snektech_spraypattern", owner.player).SetString(currentPattern);
         owner.A_Log("Selected spray pattern: "..currentPattern, true);
 
         // Current pattern is referenced in the help text, so reset