8024344: PPC64 (part 112): C argument in register AND stack slot

On PPC, the first 13 floating point arguments to C calls are passed in floating point registers. Also, all but the first 8 arguments are passed on the stack. So there can be floating point arguments that are passed on the stack and in a register. We duplicate the regs datastructure in c_calling_convention() to represent this.

Reviewed-by: kvn, cjplummer

hotspot/src/cpu/zero/vm/sharedRuntime_zero.cpp

@@ -135,6 +135,7 @@ RuntimeStub* SharedRuntime::generate_resolve_blob(address destination, const cha
 
 int SharedRuntime::c_calling_convention(const BasicType *sig_bt,
                                          VMRegPair *regs,
+                                         VMRegPair *regs2,
                                          int total_args_passed) {
   ShouldNotCallThis();
   return 0;