Fix Valgrind reports of test branching on uninitialized data.

Fix Valgrind reports of test branching on uninitialized data.

Fixes reports like:
[07:10:01.235147] [ 71/188] (9) Serialization
[07:10:01.235186] ==20052== Thread 3:
[07:10:01.235223] ==20052== Conditional jump or move depends on uninitialised value(s)
[07:10:01.235259] ==20052==    at 0x546632: SkRRect::setRectRadii(SkRect const&, SkPoint const*) (SkRect.h:426)
[07:10:01.735876] ==20052==    by 0x546FB7: SkRRect::readFromMemory(void const*, unsigned long) (SkRRect.cpp:362)
[07:10:01.735965] ==20052==    by 0x47F87F: Tests(skiatest::Reporter*) (SerializationTest.cpp:20)
[07:10:01.736007] ==20052==    by 0x480367: skiatest::SerializationClass::onRun(skiatest::Reporter*) (SerializationTest.cpp:212)
[07:10:01.736048] ==20052==    by 0x4881DA: skiatest::Test::run() (Test.cpp:109)
[07:10:01.736086] ==20052==    by 0x482516: SkTestRunnable::run() (skia_test.cpp:155)
[07:10:01.736122] ==20052==    by 0x6236E5: SkThreadPool::Loop(void*) (SkThreadPool.cpp:97)
[07:10:01.736158] ==20052==    by 0x62DDB2: thread_start(void*) (SkThreadUtils_pthread.cpp:66)
[07:10:01.736192] ==20052==    by 0x4E39E99: start_thread (pthread_create.c:308)
[07:10:01.736228] ==20052==    by 0x6A5BCCC: clone (clone.S:112)
[07:10:01.736262] ==20052==  Uninitialised value was created by a stack allocation
[07:10:01.736296] ==20052==    at 0x47EC6A: Tests(skiatest::Reporter*) (SerializationTest.cpp:155)

git-svn-id: http://skia.googlecode.com/svn/trunk@12419 2bbb7eff-a529-9590-31e7-b0007b416f81