Create a new top-level CMakeLists.txt file to control building thunk
and ROCr. kfdtest and rocrtest are built separately.
Most of the cmake code that existed for thunk, ROCr, rocrtst and kfdtest
still reside in their respective CMakeLists.txt files, except the
CPack packaging directives which have been moved to the top-level
CMakeLists.txt.
Change-Id: I1a537359029504af8b1abb324bc6f0d75d98471e
Chris Freehill