[tests] fix compile+linking issues with PlayTime (#3345)

fixes linking + comp issues but not the test themselves, who have now became invalid

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Co-authored-by: DraVee <caiooliveirafarias0@gmail.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3345
Reviewed-by: DraVee <dravee@eden-emu.dev>
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/tests/common/undefined_fix.cpp

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "frontend_common/play_time_manager.h"
+
+namespace PlayTime {
+
+PlayTimeManager::PlayTimeManager() {}
+PlayTimeManager::~PlayTimeManager() {}
+u64 PlayTimeManager::GetPlayTime(u64 program_id) const {
+    return 0;
+}
+
+} // namespace PlayTime