[Driver][SYCL][NFC] Add help information for -Wno-sycl-strict (#2570)

-Wno-sycl-strict is used in the compatibility tool user guide.  Add to the
help to provide additional (if minimal) information.

Author: mdtoguchi

clang/include/clang/Driver/Options.td

@@ -498,6 +498,7 @@ def Wno_nonportable_cfstrings : Joined<["-"], "Wno-nonportable-cfstrings">, Grou
   Flags<[CC1Option]>;
 def Wnonportable_cfstrings : Joined<["-"], "Wnonportable-cfstrings">, Group<W_Group>,
   Flags<[CC1Option]>;
+def Wno_sycl_strict : Joined<["-"], "Wno-sycl-strict">, Group<W_Group>, HelpText<"Disable warnings which enforce strict SYCL language compatibility.">;
 def Wp_COMMA : CommaJoined<["-"], "Wp,">,
   HelpText<"Pass the comma separated arguments in <arg> to the preprocessor">,
   MetaVarName<"<arg>">, Group<Preprocessor_Group>;