Compile HIP runtime with hidden visibility by default (#1303)

* add default visibility to most APIs in program_state

* remove unwanted C++ headers

* Add symbol visibility pragmas and compiler flags

* Add visibility attribute to APIs in channel_descriptor and hip_hcc

* remove unused headers

* simplify build flags with hcc

* add pragma visibility hidden to functional_grid_launch

* [CMake] add gfx908 back

src/hip_hcc.cpp

@@ -46,6 +46,7 @@ THE SOFTWARE.
 #include "hsa/hsa_ext_image.h"
 #include "hip/hip_runtime.h"
 #include "hip_hcc_internal.h"
+#include "hip/hip_hcc.h"
 #include "trace_helper.h"
 #include "env.h"