Fix Windows compilation error in AdbClientTest.cpp

Replace direct setenv() call with set_env() helper function that
handles cross-platform differences (using _putenv_s on Windows
and setenv on other platforms). This fixes the build failure:

error C3861: 'setenv': identifier not found

Author: cs01

lldb/unittests/Platform/Android/AdbClientTest.cpp

@@ -113,7 +113,7 @@ TEST_F(AdbClientTest, RealTcpConnection) {
   ASSERT_NE(unused_port, 0) << "Failed to find an unused port";
 
   std::string port_str = std::to_string(unused_port);
-  setenv("ANDROID_ADB_SERVER_PORT", port_str.c_str(), 1);
+  set_env("ANDROID_ADB_SERVER_PORT", port_str.c_str());
 
   AdbClient client;
   const auto status1 = client.Connect();