http: Reduce scope of a variable in parse_content_encoding()

Also fixes an unused variable warning with zlib disabled.

libavformat/http.c

@@ -384,11 +384,11 @@ static void parse_content_range(URLContext *h, const char *p)
 
 static int parse_content_encoding(URLContext *h, const char *p)
 {
-    HTTPContext *s = h->priv_data;
-
     if (!av_strncasecmp(p, "gzip", 4) ||
         !av_strncasecmp(p, "deflate", 7)) {
 #if CONFIG_ZLIB
+        HTTPContext *s = h->priv_data;
+
         s->compressed = 1;
         inflateEnd(&s->inflate_stream);
         if (inflateInit2(&s->inflate_stream, 32 + 15) != Z_OK) {