[turbofan] Spill rsi and rdi in their existing locations.

src/compiler/linkage.h

Index: src/compiler/linkage.h
diff --git a/src/compiler/linkage.h b/src/compiler/linkage.h
index 0f4b8db1c448055bc4568d5673bbf0b26a53fce5..9e25a99ea6799ee9affdfa41a6adc05b4742554e 100644
--- a/src/compiler/linkage.h
+++ b/src/compiler/linkage.h
@@ -317,6 +317,9 @@ class Linkage : public ZoneObject {
     return incoming_->GetReturnType(index);
   }
 
+  bool ParameterHasSecondaryLocation(int index) const;
+  LinkageLocation GetParameterSecondaryLocation(int index) const;
+
   // Get the frame offset for a given spill slot. The location depends on the
   // calling convention and the specific frame layout, and may thus be
   // architecture-specific. Negative spill slots indicate arguments on the