re PR c++/23839 (ICE: expected var_decl, have parm_decl in cxx_mark_addressable, at cp/typeck.c:4343)

	PR c++/23839
	* typeck.c (cxx_mark_addressable): Only check DECL_HARD_REGISTER
	for VAR_DECLs.

	PR c++/23839
	* g++.dg/parse/register1.C: New test.

From-SVN: r104225