Enabled gcc for hip host code (#1214)

* Enabled gcc for hip host code

* Adding tests for hip code + (gcc & g++), without kernels

* Excluding nvcc platforms for gcc and g++ tests + Addressing review comments

* minor code clean-up

* Add rocm include path

* Added relative path for library

* Hiding non supported functions for gcc

* Incorporating review comments


[ROCm/clr commit: f23c1a1499]

projects/clr/hipamd/include/hip/hip_runtime_api.h

@@ -255,6 +255,8 @@ typedef enum __HIP_NODISCARD hipError_t {
         1071,    ///< Produced when the IPC memory attach failed from ROCr.
     hipErrorAssert =
         1081,    ///< Produced when the kernel calls assert.
+    hipErrorNotSupported = 
+        1082,    ///< Produced when the hip API is not supported/implemented 
     hipErrorTbd  ///< Marker that more error codes are needed.
 } hipError_t;