ROUNDU and ROUNDD evaluation stubs

PiperOrigin-RevId: 311436251
diff --git a/src/math/roundd-neonv8.c b/src/math/roundd-neonv8.c
new file mode 100644
index 0000000..6d96e03
--- /dev/null
+++ b/src/math/roundd-neonv8.c
@@ -0,0 +1,28 @@
+// Copyright 2020 Google LLC
+//
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree.
+
+#include <assert.h>
+#include <stddef.h>
+
+#include <arm_neon.h>
+
+#include <xnnpack/math-stubs.h>
+
+
+void xnn_math_f32_roundd__neonv8(
+    size_t n,
+    const float* input,
+    float* output)
+{
+  assert(n % (4 * sizeof(float)) == 0);
+
+  for (; n != 0; n -= 4 * sizeof(float)) {
+    const float32x4_t vx = vld1q_f32(input); input += 4;
+
+    const float32x4_t vy = vrndmq_f32(vx);
+
+    vst1q_f32(output, vy); output += 4;
+  }
+}