Rename hip/hip_hcc.h to hip/hip_ext.h (#1341)

* Rename hip/hip_hcc.h to hip/hip_ext.h

* Deprecate hip_hcc.h


[ROCm/clr commit: dfee3ae279]

projects/clr/hipamd/src/hip_module.cpp

@@ -25,7 +25,7 @@ THE SOFTWARE.
 #include "hip/hcc_detail/hsa_helpers.hpp"
 #include "hip/hcc_detail/program_state.hpp"
 #include "hip_hcc_internal.h"
-#include "hip/hip_hcc.h"
+#include "hip/hip_ext.h"
 #include "program_state.inl"
 #include "trace_helper.h"