Fix reproducibility issues in opkg-build

There is a sorting problem with opkg-build where the ipk generated is depending
upon the order of files on disk. The reason is the --sort option to tar only
influences the orders of files tar reads, not those passed by the -T option.

Add in a sort call to resolve this issue. To ensure consistent sorting we
also need to force to a specific locale (C) else the results are still not
deterministic.

RP 2020/2/5

Upstream-Status: Submitted [https://groups.google.com/forum/#!topic/opkg-devel/YttZ73NLrYQ]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

Index: opkg-utils-0.4.2/opkg-build
===================================================================
--- opkg-utils-0.4.2.orig/opkg-build
+++ opkg-utils-0.4.2/opkg-build
@@ -305,8 +305,10 @@ if [ ! -z "$SOURCE_DATE_EPOCH"  ]; then
     mtime_args="--mtime=@$build_date --clamp-mtime"
 fi
 
-( cd $pkg_dir/$CONTROL && find . -type f > $tmp_dir/control_list )
-( cd $pkg_dir && find . -path ./$CONTROL -prune -o -path . -o -print  > $tmp_dir/file_list )
+export LANG=C
+export LC_ALL=C
+( cd $pkg_dir/$CONTROL && find . -type f | sort > $tmp_dir/control_list )
+( cd $pkg_dir && find . -path ./$CONTROL -prune -o -path . -o -print  | sort > $tmp_dir/file_list )
 ( cd $pkg_dir && tar $ogargs $tsortargs --no-recursion $mtime_args -c $tarformat -T $tmp_dir/file_list | $compressor $compressorargs > $tmp_dir/data.tar.$cext )
 ( cd $pkg_dir/$CONTROL && tar $ogargs $tsortargs --no-recursion --mtime=@$build_date -c $tarformat -T $tmp_dir/control_list | gzip $zipargs > $tmp_dir/control.tar.gz )
 rm $tmp_dir/file_list