zeromq: add dependency on libsodium

Using TweetNaCl can result in shutdown errors from libzmq, and it
is not recommended for "production" use. libsodium is the default
recommended by the libzmq maintainers as per the discussion in:
zeromq/libzmq#2991 (comment)

Formula/zeromq.rb

@@ -3,6 +3,8 @@ class Zeromq < Formula
   homepage "https://zeromq.org/"
   url "https://github.com/zeromq/libzmq/releases/download/v4.3.3/zeromq-4.3.3.tar.gz"
   sha256 "9d9285db37ae942ed0780c016da87060497877af45094ff9e1a1ca736e3875a2"
+  license "LGPL-3.0-or-later" => { with: "LGPL-3.0-linking-exception" }
+  revision 1
 
   livecheck do
     url :head
@@ -29,6 +31,8 @@ class Zeromq < Formula
   depends_on "pkg-config" => [:build, :test]
   depends_on "xmlto" => :build
 
+  depends_on "libsodium"
+
   def install
     # Work around "error: no member named 'signbit' in the global namespace"
     if MacOS.version == :high_sierra
@@ -42,7 +46,7 @@ def install
     # https://github.com/Homebrew/homebrew-core/pull/35940#issuecomment-454177261
 
     system "./autogen.sh" if build.head?
-    system "./configure", "--disable-dependency-tracking", "--prefix=#{prefix}"
+    system "./configure", "--disable-dependency-tracking", "--prefix=#{prefix}", "--with-libsodium"
     system "make"
     system "make", "install"
   end