Replace _mm_cvtps_epi32(x) with _mm_cvttps_epi32(_mm_add_ps(0.5f), x).

tests/Sk4xTest.cpp

Index: tests/Sk4xTest.cpp
diff --git a/tests/Sk4xTest.cpp b/tests/Sk4xTest.cpp
index d7a016c3c2406a500579303916863e0551385e46..8c3b977b5bf5f609f5df4fe4335ab71a0ef02ec6 100644
--- a/tests/Sk4xTest.cpp
+++ b/tests/Sk4xTest.cpp
@@ -59,6 +59,9 @@ DEF_TEST(Sk4x_Conversions, r) {
     ASSERT_NE(twoi, twof.reinterpret<Sk4i>());
     ASSERT_EQ(twof, twoi.cast<Sk4f>());
     ASSERT_NE(twof, twoi.reinterpret<Sk4f>());
+
+    ASSERT_EQ(Sk4i(0,0,0,0), Sk4f(0.5f, 0.49f, 0.51f, 0.99f).cast<Sk4i>());
+    ASSERT_EQ(Sk4i(1,1,1,1), Sk4f(1.5f, 1.49f, 1.51f, 1.99f).cast<Sk4i>());
 }
 
 DEF_TEST(Sk4x_Bits, r) {