[PATCH] Generate SEH unwinding info on Win64

[Reid Kleckner]

lgtm, do you want me to commit this?

================
Comment at: lib/Target/X86/X86FrameLowering.cpp:1084
@@ +1083,3 @@
+bool X86FrameLowering::assignCalleeSavedSpillSlots(MachineFunction &MF,
+                                       const TargetRegisterInfo *TRI,
+                                       std::vector<CalleeSavedInfo> &CSI) const {
----------------
indentation, clang-format can fix it.

================
Comment at: lib/Target/X86/X86FrameLowering.cpp:1113
@@ +1112,3 @@
+
+  // Assign slots for GRPs. It increases frame size.
+  for (unsigned i = CSI.size(); i != 0; --i) {
----------------
s/GRPs/GPRs/

http://reviews.llvm.org/D4081