add launchd frpc config for mac users

conf/launchd/com.github.frpc.plist

@@ -0,0 +1,29 @@
+<?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>com.github.frpc.plist</string>
+        <key>WorkingDirectory</key>
+        <string>[frp_dir]</string>
+        <key>ProgramArguments</key>
+        <array>
+            <string>./frpc</string>
+            <string>-c</string>
+            <string>frpc.ini</string>
+        </array>
+        <key>StandardOutPath</key>
+        <string>frpc.log</string>
+        <key>StandardErrorPath</key>
+        <string>frpc.log</string>
+        <key>RunAtLoad</key>
+        <true/>
+    </dict>
+</plist>
+
+<!-- 
+# change [frp_dir] first
+mv com.github.frpc.plist ~/Library/LaunchAgents/
+launchctl load ~/Library/LaunchAgents/com.github.frpc.plist
+launchctl list | grep frp
+ -->