Introduce -f{no-}spell-checking options to enable/disable

spell-checking. By default, spell-checking is enabled for Clang
(obviously) but disabled in CIndex for performance reasons.

llvm-svn: 107992

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1321,6 +1321,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.Static = Args.hasArg(OPT_static_define);
   Opts.DumpRecordLayouts = Args.hasArg(OPT_fdump_record_layouts);
   Opts.DumpVTableLayouts = Args.hasArg(OPT_fdump_vtable_layouts);
+  Opts.SpellChecking = !Args.hasArg(OPT_fno_spell_checking);
   Opts.NoBitFieldTypeAlign = Args.hasArg(OPT_fno_bitfield_type_align);
   Opts.OptimizeSize = 0;