support format CL_ABGR (#1474)
support format CL_ABGR (#1474)

* support format CL_ABGR

add code to handle format CL_ABGR

* Update imageHelpers.h

* fix format
KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS,KhronosGroup/OpenCL-CTS