nfs-utils initscript uses killall option not available in Alpine

At https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/main/nfs-utils/nfs.initd#L58 ,

killall -q -HUP rpc.idmapd

attempts to pass the signal as a bare option, but the version of killall on Alpine doesn't support that way of specifying the signal, so it just does this:

# rc-service nfs start
 * Starting rpcbind ...                                                                         [ ok ]
 * Starting NFS statd ...                                                                       [ ok ]
Usage: killall [OPTION]... [--] NAME...
---snip---

I suspect that fixing this is as easy as using

killall -q -s HUP rpc.idmapd

but I'm no expert (I'm just a user trying to run an NFS server on Alpine).