btrfs-progs: build: Do not use cp -a to install library links

btrfs-progs: build: Do not use cp -a to install library links

Using cp -a to install files will preserve the ownership of the original
files (if possible), which is typically not wanted. E.g. if the files
were built by a normal user, but are being installed by root, then the
installed files would maintain the UIDs/GIDs of the user that built the
files rather than be owned by root.

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>