use sk_bzero to init level, since I got the number of 0s wrong using { }

git-svn-id: http://skia.googlecode.com/svn/trunk@10308 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/MipMapTest.cpp b/tests/MipMapTest.cpp
index cde0ef6..3988273 100644
--- a/tests/MipMapTest.cpp
+++ b/tests/MipMapTest.cpp
@@ -31,7 +31,8 @@
         REPORTER_ASSERT(reporter, !mm->extractLevel(SK_Scalar1, NULL));
         REPORTER_ASSERT(reporter, !mm->extractLevel(SK_Scalar1 * 2, NULL));
 
-        SkMipMap::Level prevLevel = { 0, 0, 0, 0 };
+        SkMipMap::Level prevLevel;
+        sk_bzero(&prevLevel, sizeof(prevLevel));
 
         SkScalar scale = SK_Scalar1;
         for (int j = 0; j < 30; ++j) {