reshape_init only wants to work on BRACE_ENCLOSED_INITIALIZER_P, i.e. raw
initializer lists, and here was getting a CONSTRUCTOR that had already been
processed for type A<int>.  maybe_aggr_guide should also use that test.

gcc/cp/ChangeLog
2020-03-10  Jason Merrill  <jason@redhat.com>

	PR c++/93956
	* pt.c (maybe_aggr_guide): Check BRACE_ENCLOSED_INITIALIZER_P.