Fix typo in Vector lerp()

Change-Id: Id09bcb2b9ecfb90321ab94d3d9589055f0234252
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31769
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/Device/Vector.cpp

diff --git a/src/Device/Vector.cpp b/src/Device/Vector.cpp
index 258233b..b58f15e 100644
--- a/src/Device/Vector.cpp
+++ b/src/Device/Vector.cpp
@@ -170,6 +170,6 @@
 	{
 		return Vector(u.x + t * (v.x - u.x),
 		              u.y + t * (v.y - u.y),
-					  u.z + t * (v.z - u.x));
+		              u.z + t * (v.z - u.z));
 	}
 }

src/Renderer/Vector.cpp

diff --git a/src/Renderer/Vector.cpp b/src/Renderer/Vector.cpp
index 4a02534..8721639 100644
--- a/src/Renderer/Vector.cpp
+++ b/src/Renderer/Vector.cpp
@@ -170,6 +170,6 @@
 	{
 		return Vector(u.x + t * (v.x - u.x),
 		              u.y + t * (v.y - u.y),
-					  u.z + t * (v.z - u.x));
+		              u.z + t * (v.z - u.z));
 	}
 }