Add help text for -nogpuinc

Differential Revision: https://reviews.llvm.org/D92339

Author: yxsamliu

clang/include/clang/Driver/Options.td

@@ -2873,7 +2873,8 @@ def no_pedantic : Flag<["-", "--"], "no-pedantic">, Group<pedantic_Group>;
 def no__dead__strip__inits__and__terms : Flag<["-"], "no_dead_strip_inits_and_terms">;
 def nobuiltininc : Flag<["-"], "nobuiltininc">, Flags<[CC1Option, CoreOption]>,
   HelpText<"Disable builtin #include directories">;
-def nogpuinc : Flag<["-"], "nogpuinc">;
+def nogpuinc : Flag<["-"], "nogpuinc">, HelpText<"Do not add include paths for CUDA/HIP and"
+  " do not include the default CUDA/HIP wrapper headers">;
 def : Flag<["-"], "nocudainc">, Alias<nogpuinc>;
 def nogpulib : Flag<["-"], "nogpulib">,
   HelpText<"Do not link device library for CUDA/HIP device compilation">;