[colord] NULL checksum prevents loading of two different profiles

[Alexey Galakhov]

Hi,

The new CdIccStore sometimes behaves strangely:

(xiccd:5711): libcolord-DEBUG: CdIccStore: Failed to add
/home/agalakhov/.local/share/icc/EpsonPhoto-Epson.icc as profile
/home/agalakhov/.local/share/icc/Lomond Matte Epson Ink.icc already
exists with the same checksum of (null)

The profiles are created by hand from argyll and are different.

This is xiccd "new-libcolord" branch with colord 1.0.2 (I did not
upgrade yet since I want to be compatible with Debian).

Regards,
Alex