Tessellate on worker threads

Tessellate and cache (where possible) shadow and round rect
tessellation tasks.

Change-Id: I2cfda8e11d83d51ea74af871235cf26e8f831d40
diff --git a/libs/hwui/utils/MathUtils.h b/libs/hwui/utils/MathUtils.h
index 997acde2..65f1663 100644
--- a/libs/hwui/utils/MathUtils.h
+++ b/libs/hwui/utils/MathUtils.h
@@ -38,6 +38,10 @@
         return isZero(valueA - valueB);
     }
 
+    inline static int max(int a, int b) {
+        return a > b ? a : b;
+    }
+
     inline static int min(int a, int b) {
         return a < b ? a : b;
     }