avcodec/libx265: fix build error

x265_sei is available since X265_BUILD 88. Bump required version
to 89 to fix the regression from commit 1f58503013, and remove a
conditional compilation.

Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>

configure

@@ -6723,7 +6723,7 @@ enabled libx264           && require_pkg_config libx264 x264 "stdint.h x264.h" x
                              require_cpp_condition libx264 x264.h "X264_BUILD >= 158"; } &&
                              check_cpp_condition libx262 x264.h "X264_MPEG2"
 enabled libx265           && require_pkg_config libx265 x265 x265.h x265_api_get &&
-                             require_cpp_condition libx265 x265.h "X265_BUILD >= 70"
+                             require_cpp_condition libx265 x265.h "X265_BUILD >= 89"
 enabled libxavs           && require libxavs "stdint.h xavs.h" xavs_encoder_encode "-lxavs $pthreads_extralibs $libm_extralibs"
 enabled libxavs2          && require_pkg_config libxavs2 "xavs2 >= 1.3.0" "stdint.h xavs2.h" xavs2_api_get
 enabled libxvid           && require libxvid xvid.h xvid_global -lxvidcore

libavcodec/libx265.c

@@ -295,7 +295,6 @@ static av_cold int libx265_encode_init(AVCodecContext *avctx)
             return ret;
     }
 
-#if X265_BUILD >= 89
     if (avctx->qmin >= 0) {
         ret = libx265_param_parse_int(avctx, "qpmin", avctx->qmin);
         if (ret < 0)
@@ -306,7 +305,6 @@ static av_cold int libx265_encode_init(AVCodecContext *avctx)
         if (ret < 0)
             return ret;
     }
-#endif
     if (avctx->max_qdiff >= 0) {
         ret = libx265_param_parse_int(avctx, "qpstep", avctx->max_qdiff);
         if (ret < 0)