* set gDeviceType in testharness.c, also moved gTestRounding to imageHelpers.cpp & .h and removed duplicate code from host_atomics.cpp
* Cleaned up some redundant code
* Reversed the change in testharness.c
* Moved all instances of gDeviceType to imageHelper.cpp
* Missed one instance of gDeviceType
* Removed all instances of extern cl_device_type gDeviceType, except in imageHelpers.h