d3dx9: D3DXQuaternionToAxisAngle should not crash on NULLs in output parameters.

dlls/d3dx9_36/math.c

@@ -1652,10 +1652,14 @@ void WINAPI D3DXQuaternionToAxisAngle(const D3DXQUATERNION *pq, D3DXVECTOR3 *pax
 {
     TRACE("pq %p, paxis %p, pangle %p\n", pq, paxis, pangle);
 
-    paxis->x = pq->x;
-    paxis->y = pq->y;
-    paxis->z = pq->z;
-    *pangle = 2.0f * acosf(pq->w);
+    if (paxis)
+    {
+        paxis->x = pq->x;
+        paxis->y = pq->y;
+        paxis->z = pq->z;
+    }
+    if (pangle)
+        *pangle = 2.0f * acosf(pq->w);
 }
 
 /*_________________D3DXVec2_____________________*/

dlls/d3dx9_36/tests/math.c

@@ -1019,9 +1019,14 @@ static void D3DXQuaternionTest(void)
     /* Test the null quaternion */
     expectedvec.x = 0.0f; expectedvec.y = 0.0f; expectedvec.z = 0.0f;
     expected = 3.141593f;
-    D3DXQuaternionToAxisAngle(&nul,&axis,&angle);
-    expect_vec3(expectedvec,axis);
-    ok(relative_error(angle, expected ) < admitted_error, "Expected: %f, Got: %f\n", expected, angle);
+    D3DXQuaternionToAxisAngle(&nul, &axis, &angle);
+    expect_vec3(expectedvec, axis);
+    ok(relative_error(angle, expected) < admitted_error, "Expected: %f, Got: %f\n", expected, angle);
+
+    D3DXQuaternionToAxisAngle(&nul, &axis, NULL);
+    D3DXQuaternionToAxisAngle(&nul, NULL, &angle);
+    expect_vec3(expectedvec, axis);
+    ok(relative_error(angle, expected) < admitted_error, "Expected: %f, Got: %f\n", expected, angle);
 }
 
 static void D3DXVector2Test(void)