NVHPC: Support SYSTEM include directories

Fixed #22834

Modules/Compiler/NVHPC.cmake

@@ -12,4 +12,5 @@ include(Compiler/PGI)
 
 macro(__compiler_nvhpc lang)
   # Logic specific to NVHPC.
+  set(CMAKE_INCLUDE_SYSTEM_FLAG_${lang} "-isystem ")
 endmacro()

Tests/IncludeDirectories/CMakeLists.txt

@@ -3,6 +3,7 @@ project(IncludeDirectories)
 
 if (((CMAKE_C_COMPILER_ID STREQUAL GNU AND CMAKE_C_COMPILER_VERSION VERSION_GREATER 4.4)
     OR (CMAKE_C_COMPILER_ID STREQUAL Clang AND NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+    OR CMAKE_C_COMPILER_ID STREQUAL NVHPC
     OR CMAKE_C_COMPILER_ID STREQUAL AppleClang
     OR ("x${CMAKE_C_COMPILER_ID}" STREQUAL "xMSVC" AND
        CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL "19.29.30036.3" AND