Try to fix build.

af_afstats_void.patch

@@ -0,0 +1,13 @@
+diff --git a/libavfilter/af_astats.c b/libavfilter/af_astats.c
+index 1ec56d72cc..bb9a23a017 100644
+--- a/libavfilter/af_astats.c
++++ b/libavfilter/af_astats.c
+@@ -496,7 +496,7 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
+
+ #define UPDATE_STATS(planar, type, sample, normalizer_suffix, int_sample) \
+     if ((s->measure_overall | s->measure_perchannel) & ~MEASURE_MINMAXPEAK) {                          \
+-        UPDATE_STATS_##planar(type, update_stat(s, p, sample, sample normalizer_suffix, int_sample), s->is_float ? update_float_stat(s, p, sample) : s->is_double ? update_double_stat(s, p, sample) : NULL, );    \
++        UPDATE_STATS_##planar(type, update_stat(s, p, sample, sample normalizer_suffix, int_sample), s->is_float ? update_float_stat(s, p, sample) : s->is_double ? update_double_stat(s, p, sample) : (void)NULL, ); \
+     } else {                                                                                           \
+         UPDATE_STATS_##planar(type, update_minmax(s, p, sample), , p->nmin = p->min normalizer_suffix; p->nmax = p->max normalizer_suffix;); \
+     }

install.bat

@@ -2,6 +2,7 @@
 git submodule update --init --recursive --depth 1000
 pushd ffmpeg
 git apply ../create-lib-libraries.patch
+git apply ../af_afstats_void.patch
 popd
 if not exist c:\nasm-2.14.02-win64.zip ( curl -o c:\nasm-2.14.02-win64.zip https://www.nasm.us/pub/nasm/releasebuilds/2.14.02/win64/nasm-2.14.02-win64.zip )
 7z x c:\nasm-2.14.02-win64.zip -oc:\