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

tests/src/hipHcc.cpp

@@ -30,7 +30,7 @@ THE SOFTWARE.
 #include <stdio.h>
 #include <iostream>
 #include "hip/hip_runtime.h"
-#include "hip/hip_hcc.h"
+#include "hip/hip_ext.h"
 #include "test_common.h"
 
 #define CHECK(error)                                                                               \