[NDS32] Emit stack push instructions for varargs at prologue stage and emit...

[NDS32] Emit stack push instructions for varargs at prologue stage and emit...

[NDS32]  Emit stack push instructions for varargs at prologue stage and
         emit stack adjustment instructions for varargs at epilogue stage.

  -- Note that we do not need to handle it in v3push/v3pop prologue/epilogue
     expanding because we do not apply v3push/v3pop for variadic function.

	* config/nds32/nds32.c (nds32_expand_prologue): Emit stack push
	instructions for varargs implementation.
	(nds32_expand_epilogue): Emit stack adjustment instructions for
	varargs implementation.

From-SVN: r214867