* Use std::vector for format lists in images suite
Avoids memory deallocation issues and generally simplifies the code.
* Fixup formatting with git-clang-format
* 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
Some of the setup functionality is already there in the test harness, so
use that and remove the duplicated code from within the suite.
Signed-off-by: Radek Szymanski <radek.szymanski@arm.com>