[flang][Driver] Support -Qunused-arguments (#107462)

This partially addresses:
#89888

Author: tarunprabhu

clang/include/clang/Driver/Options.td

@@ -949,7 +949,7 @@ def : Flag<["-"], "fident">, Group<f_Group>, Alias<Qy>,
 def : Flag<["-"], "fno-ident">, Group<f_Group>, Alias<Qn>,
   Visibility<[ClangOption, CLOption, DXCOption, CC1Option]>;
 def Qunused_arguments : Flag<["-"], "Qunused-arguments">,
-  Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption]>,
+  Flags<[NoXarchOption]>, Visibility<[ClangOption, CLOption, DXCOption, FlangOption]>,
   HelpText<"Don't emit warning for unused driver arguments">;
 def Q : Flag<["-"], "Q">, IgnoredGCCCompat;
 def S : Flag<["-"], "S">, Flags<[NoXarchOption]>,

flang/test/Driver/q-unused-arguments.f90

@@ -0,0 +1,5 @@
+! RUN: %flang -Qunused-arguments -c -o /dev/null %s -L. 2>&1 | FileCheck %s --allow-empty
+
+! CHECK-NOT: argument unused during compilation
+
+end program