addS EAF_NOT_RETURNED_DIRECTLY

addS EAF_NOT_RETURNED_DIRECTLY

addS EAF_NOT_RETURNED_DIRECTLY which works similarly as
EAF_NODIRECTESCAPE.  Values pointed to by a given argument may be returned but
not the argument itself.  This helps PTA quite noticeably because we mostly
care about tracking points to which given memory location can escape.

gcc/ChangeLog:

	* tree-core.h (EAF_NOT_RETURNED_DIRECTLY): New flag.
	(EAF_NOREAD): Renumber.
	* ipa-modref.c (dump_eaf_flags): Dump EAF_NOT_RETURNED_DIRECTLY.
	(remove_useless_eaf_flags): Handle EAF_NOT_RETURNED_DIRECTLY
	(deref_flags): Likewise.
	(modref_lattice::init): Likewise.
	(modref_lattice::merge): Likewise.
	(merge_call_lhs_flags): Likewise.
	(analyze_ssa_name_flags): Likewise.
	(modref_merge_call_site_flags): Likewise.
	* tree-ssa-structalias.c (handle_call_arg): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/ipa/modref-1.C: Update template.
	* gcc.dg/tree-ssa/modref-10.c: New test.