[clang/driver] Add `-gno-modules` as the negative version of `-gmodules`

clang/include/clang/Driver/Options.td

 def ggnu_pubnames : Flag<["-"], "ggnu-pubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;
 def gno_gnu_pubnames : Flag<["-"], "gno-gnu-pubnames">, Group<g_flags_Group>;
 def gpubnames : Flag<["-"], "gpubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;
 def gno_pubnames : Flag<["-"], "gno-pubnames">, Group<g_flags_Group>;
 def gdwarf_aranges : Flag<["-"], "gdwarf-aranges">, Group<g_flags_Group>;
 def gmodules : Flag <["-"], "gmodules">, Group<gN_Group>,
   HelpText<"Generate debug info with external references to clang modules"
            " or precompiled headers">;
+def gno_modules : Flag <["-"], "gno-modules">, Group<gN_Group>;
 def gz_EQ : Joined<["-"], "gz=">, Group<g_flags_Group>,
     HelpText<"DWARF debug sections compression type">;
 def gz : Flag<["-"], "gz">, Alias<gz_EQ>, AliasArgs<["zlib"]>, Group<g_flags_Group>;
 def gembed_source : Flag<["-"], "gembed-source">, Group<g_flags_Group>, Flags<[CC1Option]>,
     HelpText<"Embed source text in DWARF debug sections">,
     MarshallingInfoFlag<CodeGenOpts<"EmbedSource">>;
 def gno_embed_source : Flag<["-"], "gno-embed-source">, Group<g_flags_Group>,
     Flags<[NoXarchOption]>,

clang/lib/Driver/ToolChains/Clang.cpp

if (const Arg *A = Args.getLastArg(options::OPT_gcolumn_info))
     (void)checkDebugInfoOption(A, Args, D, TC);
   if (!Args.hasFlag(options::OPT_gcolumn_info, options::OPT_gno_column_info,
                     !EmitCodeView &&
                         (DebuggerTuning != llvm::DebuggerKind::SCE &&
                          DebuggerTuning != llvm::DebuggerKind::DBX)))
     CmdArgs.push_back("-gno-column-info");
 
   // FIXME: Move backend command line options to the module.
-  // If -gline-tables-only or -gline-directives-only is the last option it wins.
-  if (const Arg *A = Args.getLastArg(options::OPT_gmodules))
-    if (checkDebugInfoOption(A, Args, D, TC)) {
+  if (Args.hasFlag(options::OPT_gmodules, options::OPT_gno_modules, false)) {
+    // If -gline-tables-only or -gline-directives-only is the last option it
+    // wins.
+    if (checkDebugInfoOption(Args.getLastArg(options::OPT_gmodules), Args, D,
+                             TC)) {
       if (DebugInfoKind != codegenoptions::DebugLineTablesOnly &&
           DebugInfoKind != codegenoptions::DebugDirectivesOnly) {
         DebugInfoKind = codegenoptions::DebugInfoConstructor;
         CmdArgs.push_back("-dwarf-ext-refs");
         CmdArgs.push_back("-fmodule-format=obj");
       }
     }
+  }
 
   if (T.isOSBinFormatELF() && SplitDWARFInlining)
     CmdArgs.push_back("-fsplit-dwarf-inlining");
 
   // After we've dealt with all combinations of things that could
   // make DebugInfoKind be other than None or DebugLineTablesOnly,
   // figure out if we need to "upgrade" it to standalone debug info.
   // We parse these two '-f' options whether or not they will be used,

clang/test/Driver/debug-options.c

 // RUN:        | FileCheck -check-prefix=GEXTREFS %s
 //
 // RUN: %clang -### -gmodules -gline-tables-only %s 2>&1 \
 // RUN:        | FileCheck -check-prefix=GLTO_ONLY %s
 //
 // RUN: %clang -### -target %itanium_abi_triple -gmodules -gline-directives-only %s 2>&1 \
 // RUN:        | FileCheck -check-prefix=GLIO_ONLY %s
 //
+// RUN: %clang -### -gmodules -gno-modules %s 2>&1 \
+// RUN:        | FileCheck -check-prefix=NOGEXTREFS %s
+//
 // NOG_PS: "-cc1"
 // NOG_PS-NOT: "-dwarf-version=
 // NOG_PS: "-generate-arange-section"
 // NOG_PS-NOT: "-dwarf-version=
 //
 // G_ERR: error: unknown argument:
 //
 // G_NO: "-cc1"

 // NOFDTSE-NOT: error: unsupported option '-fdebug-types-section' for target 'x86_64-apple-darwin'
 //
 // CI-NOT: "-gno-column-info"
 //
 // NOCI-DAG: "-gno-column-info"
 //
 // GEXTREFS: "-dwarf-ext-refs" "-fmodule-format=obj"
 // GEXTREFS: "-debug-info-kind={{standalone|constructor}}"
+// NOGEXTREFS-NOT: -dwarf-ext-refs
 
 // RUN: not %clang -cc1 -debug-info-kind=watkind 2>&1 | FileCheck -check-prefix=BADSTRING1 %s
 // BADSTRING1: error: invalid value 'watkind' in '-debug-info-kind=watkind'
 // RUN: not %clang -cc1 -debugger-tuning=gmodal 2>&1 | FileCheck -check-prefix=BADSTRING2 %s
 // BADSTRING2: error: invalid value 'gmodal' in '-debugger-tuning=gmodal'
 
 // RUN: %clang -### -fdebug-macro    %s 2>&1 | FileCheck -check-prefix=MACRO %s
 // RUN: %clang -### -fno-debug-macro %s 2>&1 | FileCheck -check-prefix=NOMACRO %s