Log Message:
babl: Update to 0.1.78

Changelog:
2020-06-07 babl-0.1.78
Bugfix release - mutex and atomicity related issues.

2020-05-27 babl-0.1.76
Wrap hue in HSV, HSL, HCY. Fix black pullout in non ICC CMYK
conversion. Added AV2 gamme u8->linear float conversions.  VAPI file generation
for vala integration. Adjusted strategy for conversion selection, trades back
warm-up time for missing some fast multi-step conversions.