re PR c++/92992 (Side-effects dropped when decltype(nullptr) typed expression is passed to ellipsis)

	PR c++/92992
	* call.c (convert_arg_to_ellipsis): For decltype(nullptr) arguments
	that have side-effects use cp_build_compound_expr.

	* g++.dg/cpp0x/nullptr45.C: New test.

From-SVN: r279680