bitcoin: add plist (#18704)

Formula/bitcoin.rb

@@ -35,6 +35,26 @@ class Bitcoin < Formula
     system "make", "install"
   end
 
+  plist_options :manual => "bitcoind"
+
+  def plist; <<-EOS.undent
+    <?xml version="1.0" encoding="UTF-8"?>
+    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+    <plist version="1.0">
+    <dict>
+      <key>Label</key>
+      <string>#{plist_name}</string>
+      <key>ProgramArguments</key>
+      <array>
+        <string>#{opt_bin}/bitcoind</string>
+      </array>
+      <key>RunAtLoad</key>
+      <true/>
+    </dict>
+    </plist>
+    EOS
+  end
+
   test do
     system "#{bin}/test_bitcoin"
   end