Use ro.hw_timeout_multiplier in Readback deadline

... to give SwiftShader some more time to complete.

Bug: b/354222246
Test: CtsUiRenderingTestCases x100
Change-Id: I943249a84daa873508bddcfc532048ef71eb4129
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index ec53070..f464043 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -338,6 +338,8 @@
     static bool clipSurfaceViews;
     static bool hdr10bitPlus;
 
+    static int timeoutMultiplier;
+
     static StretchEffectBehavior getStretchEffectBehavior() {
         return stretchEffectBehavior;
     }