Allow for use of either Qt5 or Qt6

[rm5248]

Since Qt #defines emit, the LogLog class fails to compile properly as the function prototype no longer exists.

Oddly this works fine in Qt5, but it breaks with Qt6. We can work around it with defining QT_NO_KEYWORDS, but this would require anybody who links with us and with Qt to define this as well, which is not a good requirement for a library.

[rm5248]

Note: if removing the emit function prototype breaks the ABI(I don't think it should since it's private static and is only inside of the LogLog class), we can always wrap it in a preprocessor macro that is only defined when building the library itself.