clang-tidy: add explicit deleted constructors

Found with cppcoreguidelines-special-member-functions

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/lib/curl/Global.cxx

@@ -57,6 +57,9 @@ public:
 		   better solution? */
 	}
 
+	CurlSocket(const CurlSocket &) = delete;
+	CurlSocket &operator=(const CurlSocket &) = delete;
+
 	auto &GetEventLoop() const noexcept {
 		return socket_event.GetEventLoop();
 	}