Fix T46030: Strange behavior of Cycles Brick Texture

Added some extra seed to the hash, so it's now less likely to give repetitive
patters at values around zero.

This will change distribution of bricks for existing files. but it's something
inevitable.

intern/cycles/kernel/shaders/node_brick_texture.osl

@@ -22,6 +22,7 @@
 float brick_noise(int n) /* fast integer noise */
 {
 	int nn;
+	n = (n + 1013) & 2147483647;
 	n = (n >> 13) ^ n;
 	nn = (n * (n * n * 60493 + 19990303) + 1376312589) & 2147483647;
 	return 0.5 * ((float)nn / 1073741824.0);

intern/cycles/kernel/svm/svm_brick.h

@@ -21,6 +21,7 @@ CCL_NAMESPACE_BEGIN
 ccl_device_noinline float brick_noise(int n) /* fast integer noise */
 {
 	int nn;
+	n = (n + 1013) & 0x7fffffff;
 	n = (n >> 13) ^ n;
 	nn = (n * (n * n * 60493 + 19990303) + 1376312589) & 0x7fffffff;
 	return 0.5f * ((float)nn / 1073741824.0f);