Delete explicit copy assignment operator

This is causing a -Wdeprecated-copy error with Clang 14

Change-Id: Id6f43431892f28f67c25bd7de69888a424cd9ce6
Bug: oss-fuzz:38346
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/57028
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
diff --git a/src/Renderer/Matrix.hpp b/src/Renderer/Matrix.hpp
index b9fce24..bec05d0 100644
--- a/src/Renderer/Matrix.hpp
+++ b/src/Renderer/Matrix.hpp
@@ -36,8 +36,6 @@
 		       float m41, float m42, float m43, float m44);
 		Matrix(const Vector &v1, const Vector &v2, const Vector &v3);   // Column vectors
 
-		Matrix &operator=(const Matrix &N) = default;
-
 		// Row major order
 		float m[4][4];