Speed up dcrawUtils.cpp
Speed up dcrawUtils.cpp

- Don't read unused data, and just break the loop as early as possible
- Move if-else outside of for loop
ktgw0316/LightZone,ktgw0316/LightZone,ktgw0316/LightZone,ktgw0316/LightZone,ktgw0316/LightZone,ktgw0316/LightZone,ktgw0316/LightZone