tor: add option to build against Homebrew's OpenSSL

Closes Homebrew/homebrew#20793.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/tor.rb

@@ -5,10 +5,20 @@ class Tor < Formula
   url 'https://www.torproject.org/dist/tor-0.2.3.25.tar.gz'
   sha1 'ef02e5b0eb44ab1a5d6108c39bd4e28918de79dc'
 
+  option "with-brewed-openssl", "Build with Homebrew's OpenSSL instead of the system version"
+
   depends_on 'libevent'
+  depends_on 'openssl' if build.with? 'brewed-openssl'
 
   def install
-    system "./configure", "--disable-dependency-tracking", "--prefix=#{prefix}"
+    args = %W[
+      --disable-dependency-tracking
+      --prefix=#{prefix}
+    ]
+
+    args << "-with-ssl=#{Formulary.factory('openssl').opt_prefix}" if build.with? 'brewed-openssl'
+
+    system "./configure", *args
     system "make install"
   end