Fix system tray Open Sunshine (#1095)

Co-authored-by: KuleRucket <luke.d.tucker@gmail.com>
Co-authored-by: ReenigneArcher <42013603+ReenigneArcher@users.noreply.github.com>

src/system_tray.cpp

@@ -49,9 +49,11 @@ namespace system_tray {
     // this isn't ideal as it briefly shows a command window
     // but start a command built into cmd, not an executable
     std::string cmd = R"(cmd /C "start )" + url + R"(")";
-  #else  // if unix
+  #elif defined(__linux__) || defined(linux) || defined(__linux)
     // set working dir to user home directory
     working_dir = boost::filesystem::path(std::getenv("HOME"));
+    std::string cmd = R"(xdg-open ")" + url + R"(")";
+  #elif defined(__APPLE__) || defined(__MACH__)
     std::string cmd = R"(open ")" + url + R"(")";
   #endif