main/sshfs: add helper symlink to /sbin

Fixes #13366 (closed). According to this util-linux-ng message, all mount helpers should be available from /sbin.

main/sshfs/APKBUILD

 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=sshfs
 pkgver=3.7.2
-pkgrel=0
+pkgrel=1
 pkgdesc="FUSE client based on the SSH File Transfer Protocol"
 url="https://github.com/libfuse/sshfs"
 arch="all"
@@ -23,6 +23,9 @@ package() {
 	mkdir -p "$pkgdir"/usr/share/doc/$pkgname/
 	install -Dm644 README.rst ChangeLog.rst AUTHORS COPYING \
 		"$pkgdir"/usr/share/doc/$pkgname/
+
+	mkdir -p "$pkgdir"/sbin
+	ln -s /usr/sbin/mount.sshfs "$pkgdir"/sbin/mount.sshfs
 }
 
 sha512sums="