Fix handling of deferred SSA names in modref dataflow

In the testcase we fail to analyze SSA name because flag do_dataflow is set
and thus triggers early exist in analyze_ssa_name.  Fixed by disabling
early exits when handling deferred names.

gcc/ChangeLog:

2021-12-20  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/103669
	* ipa-modref.c (modref_eaf_analysis::analyze_ssa_name): Add deferred
	parameter.
	(modref_eaf_analysis::propagate): Use it.

gcc/testsuite/ChangeLog:

2021-12-20  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/103669
	* g++.dg/torture/pr103669.C: New test.