Pass unpromoted argument to promote_function_mode

This patch updates setup_incoming_promotions in combine.c to match what
is actually passed in assign_parm_setup_reg in function.c.

Backported from mainline:

gcc/

	PR rtl-optimization/64037
	* combine.c (setup_incoming_promotions): Pass the argument
	before any promotions happen to promote_function_mode.

gcc/testsuite/

	PR rtl-optimization/64037
	* g++.dg/pr64037.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_8-branch@218967 138bc75d-0d04-0410-961f-82ee72b054a4