Plumb through the -fsplit-stack option using the existing backend
support.

Caveat: Other than the existing segmented stacks support, no
claims are made of this working.

llvm-svn: 178744
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index fbf0349..611e784 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -358,6 +358,7 @@
   Opts.NumRegisterParameters = Args.getLastArgIntValue(OPT_mregparm, 0, Diags);
   Opts.NoGlobalMerge = Args.hasArg(OPT_mno_global_merge);
   Opts.NoExecStack = Args.hasArg(OPT_mno_exec_stack);
+  Opts.EnableSegmentedStacks = Args.hasArg(OPT_split_stacks);
   Opts.RelaxAll = Args.hasArg(OPT_mrelax_all);
   Opts.OmitLeafFramePointer = Args.hasArg(OPT_momit_leaf_frame_pointer);
   Opts.SaveTempLabels = Args.hasArg(OPT_msave_temp_labels);