Use an option alias to implement -gmlt

Review feedback from Reid Kleckner on r203603.

llvm-svn: 204755
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 0900649..781ec2b 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -898,8 +898,7 @@
   HelpText<"Generate source level debug information">, Flags<[CC1Option]>;
 def gline_tables_only : Flag<["-"], "gline-tables-only">, Group<g_Group>,
   HelpText<"Emit debug line number tables only">, Flags<[CC1Option]>;
-def gmlt : Flag<["-"], "gmlt">, Group<g_Group>,
-  HelpText<"Emit debug line number tables only">, Flags<[DriverOption,HelpHidden]>;
+def gmlt : Flag<["-"], "gmlt">, Alias<gline_tables_only>;
 def g0 : Flag<["-"], "g0">, Group<g_Group>;
 def g1 : Flag<["-"], "g1">, Group<g_Group>;
 def g2 : Flag<["-"], "g2">, Group<g_Group>;
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index c90fb81..ea60551 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2695,8 +2695,7 @@
   // are preserved, all other debug options are substituted with "-g".
   Args.ClaimAllArgs(options::OPT_g_Group);
   if (Arg *A = Args.getLastArg(options::OPT_g_Group)) {
-    if (A->getOption().matches(options::OPT_gline_tables_only) ||
-        A->getOption().matches(options::OPT_gmlt)) {
+    if (A->getOption().matches(options::OPT_gline_tables_only)) {
       // FIXME: we should support specifying dwarf version with
       // -gline-tables-only.
       CmdArgs.push_back("-gline-tables-only");