Don't require setting __HIP_PLATFORM_HCC__ ; Instead check if compiler is HCC.
The functions here use HCC-specific functionality so only work with HCC.
ANd they work regardless of the __HIP_PLATFORM_HCC__ setting so don't
require that.
Also remove the "hcc_detail" extra hierarchy level for hip_hcc.h as
it is not necessary. Remove hcc_detail/hip_hcc.h.
Ben Sander
9c229f7530