[CMake] Change in behaviour (regression?) in automoc in latest CMake

[Dominik Schmidt]

Moin!

With the latest release of CMake compilation of Tomahawk Player stopped 
working for us because automoc stopped producing output for a certain file.

Obviously code ifdef'ed by "#if QT_VERSION >= 0x040400" isn't scanned 
anymore. Is that on purpose?

Best regards,
Dominik

P.S.: Commit that fixed building our master: 
https://github.com/tomahawk-player/tomahawk/commit/c910e1b58f01a42b9f99222e501172576d8cad06