Workaround for libc++ include path for HIP-Clang (#1917)

HIP-Clang cuda_wrapper headers require clang include path before standard C++ include path.
However libc++ include path requires to be before clang include path.
To workaround this, we pass -isystem with the parent directory of clang include
path instead of the clang include path itself.

bin/hipcc

@@ -207,7 +207,7 @@ if ($HIP_PLATFORM eq "clang") {
     } else {
       $HIPCXXFLAGS .= " -std=c++11";
     }
-    $HIPCXXFLAGS .= " -isystem $HIP_CLANG_INCLUDE_PATH";
+    $HIPCXXFLAGS .= " -isystem $HIP_CLANG_INCLUDE_PATH/..";
     $HIPLDFLAGS .= " -L$HIP_LIB_PATH";
     if (not $isWindows) {
       $HIPLDFLAGS .= " -Wl,--rpath-link=$HIP_LIB_PATH";

include/hip/hcc_detail/hip_runtime.h

@@ -501,9 +501,14 @@ hc_get_workitem_absolute_id(int dim)
 #define __CUDA__
 #include <__clang_cuda_math_forward_declares.h>
 #include <__clang_cuda_complex_builtins.h>
-#include <cuda_wrappers/algorithm>
-#include <cuda_wrappers/complex>
-#include <cuda_wrappers/new>
+// Workaround for using libc++ with HIP-Clang.
+// The following headers requires clang include path before standard C++ include path.
+// However libc++ include path requires to be before clang include path.
+// To workaround this, we pass -isystem with the parent directory of clang include
+// path instead of the clang include path itself.
+#include <include/cuda_wrappers/algorithm>
+#include <include/cuda_wrappers/complex>
+#include <include/cuda_wrappers/new>
 #undef __CUDA__
 #pragma pop_macro("__CUDA__")
 #endif // !_OPENMP || __HIP_ENABLE_CUDA_WRAPPER_FOR_OPENMP__