Update gtx_quaternion.cpp

test/gtx/gtx_quaternion.cpp

@@ -101,7 +101,7 @@ int test_quat_lookAt()
 	glm::vec3 center(1.1f, -2.0f, 3.1416f);
 	glm::vec3 up = glm::vec3(-0.17f, 7.23f, -1.744f);
 
-	glm::quat test_quat = glm::quatLookAt(center - eye, up);
+	glm::quat test_quat = glm::quatLookAt(glm::normalize(center - eye), up);
 	glm::quat test_mat = glm::conjugate(glm::quat_cast(glm::lookAt(eye, center, up)));
 
 	Error += static_cast<int>(glm::abs(glm::length(test_quat) - 1.0f) > glm::epsilon<float>());