c++: zero_init_expr_p of dependent expression

c++: zero_init_expr_p of dependent expression

This fixes an ICE coming from mangle.c:write_expression when building the
testsuite of range-v3; the added testcase is a reduced reproducer for the ICE.

gcc/cp/ChangeLog:

	* tree.c (zero_init_expr_p): Use uses_template_parms instead of
	dependent_type_p.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/dependent3.C: New test.