cmake: Build with keyring option

Can somebody test with 
-DKEYRING_GNOME=ON
-DKEYRING_WINDOWS=ON
-DKEYRING_MAC=ON
-DKEYRING_IOS=ON
-DKEYRING_FLATFILE=ON

e.g. cmake .. -DKEYRING_GNOME=ON

I can't test Windows, Mac and iOS.

The current KWallet (KDE) implementation seems to be broken
-DKEYRING_KWALLET=ON
I put it on targetprocess.