[NDS32] Deal with nameless arguments in nds32_function_arg and nds32_function_arg_adv...

[NDS32] Deal with nameless arguments in nds32_function_arg and nds32_function_arg_advance.

  1. We have caller prepare nameless arguments in the way of calling a normal function.

     e.g. Assume a function: void va_test (int n, ...);
          When calling "va_test (6, 11, 22, 33, 44, 55, 66);",
               r0    <- 6
               r1    <- 11
               r2    <- 22
               r3    <- 33
               r4    <- 44
               r5    <- 55
            [sp + 0] <- 66

  2. Note that we DO NOT handle it for TARGET_HARD_FLOAT case.
     The TARGET_HARD_FLOAT should push all the nameless arguments into
     stack and GCC is able to take care of them itself.
     In addition, we have not implemented hard float on trunk yet.

	* config/nds32/nds32.c (nds32_function_arg): Deal with nameless
	arguments.
	(nds32_function_arg_advance): Deal with nameless arguments.
	* config/nds32/nds32.h (NDS32_ARG_PASS_IN_REG_P): Split it into ...
	(NDS32_ARG_ENTIRE_IN_GPR_REG_P): ... this one and ...
	(NDS32_ARG_PARTIAL_IN_GPR_REG_P): ... this one.

From-SVN: r214865