chore(reuse): annotate our source files with our license (#6719)

src/debug/AssertInGuiThread.hpp

@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2019 Contributors to Chatterino <https://chatterino.com>
+//
+// SPDX-License-Identifier: MIT
+
 #pragma once
 
 #include <QCoreApplication>

src/debug/Benchmark.cpp

@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2019 Contributors to Chatterino <https://chatterino.com>
+//
+// SPDX-License-Identifier: MIT
+
 #include "debug/Benchmark.hpp"
 
 #include "common/QLogging.hpp"

src/debug/Benchmark.hpp

@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2019 Contributors to Chatterino <https://chatterino.com>
+//
+// SPDX-License-Identifier: MIT
+
 #pragma once
 
 #include <QElapsedTimer>