CTF: Use static with operator

Also fix coding style in the operator.

Pick-to: 6.5
Change-Id: Ia8f85a7bb7aa2d6f55923c80f72b734fc8dbd693
Reviewed-by: Hatem ElKharashy <hatem.elkharashy@qt.io>
Reviewed-by: Janne Koskinen <janne.p.koskinen@qt.io>
Reviewed-by: Antti Määttä <antti.maatta@qt.io>

src/plugins/tracing/qctflib.cpp

@@ -31,10 +31,10 @@ static const char traceMetadataTemplate[] =
 static const size_t traceMetadataSize = sizeof(traceMetadataTemplate);
 
 template <typename T>
-QByteArray &operator<<(QByteArray &arr, T val)
+static QByteArray &operator<<(QByteArray &arr, T val)
 {
     static_assert(std::is_arithmetic_v<T>);
-    arr.append((char *)&val, sizeof(val));
+    arr.append(reinterpret_cast<char *>(&val), sizeof(val));
     return arr;
 }