Remove a few if (p) av_freep(&p) forms

Signed-off-by: Mans Rullgard <mans@mansr.com>
(cherry picked from commit 523d9407)

libavcodec/libxvidff.c

@@ -527,8 +527,7 @@ static av_cold int xvid_encode_close(AVCodecContext *avctx) {
 
     xvid_encore(x->encoder_handle, XVID_ENC_DESTROY, NULL, NULL);
 
-    if( avctx->extradata != NULL )
-        av_freep(&avctx->extradata);
+    av_freep(&avctx->extradata);
     if( x->twopassbuffer != NULL ) {
         av_free(x->twopassbuffer);
         av_free(x->old_twopassbuffer);

libavutil/tree.h

@@ -67,7 +67,7 @@ void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *ke
  *                 return av_tree_insert(rootp, key, cmp, next);
  *             }
  *             void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
- *                 if(*next) av_freep(next);
+ *                 av_freep(next);
  *                 return av_tree_insert(rootp, key, cmp, next);
  *             }
  *             @endcode

libswscale/swscale-test.c

@@ -104,8 +104,7 @@ static int doTest(uint8_t *ref[4], int refStride[4], int w, int h,
         int p;
 
         for (p = 0; p < 4; p++)
-            if (src[p])
-                av_freep(&src[p]);
+            av_freep(&src[p]);
 
         av_image_fill_linesizes(srcStride, srcFormat, srcW);
         for (p = 0; p < 4; p++) {