re PR fortran/41212 (miscompilation at -O2)

        PR fortran/41212
	* tree.h (struct tree_decl_common): Add decl_restricted_flag,
	shorten decl_common_unused.
	(DECL_RESTRICTED_P): New accessor.
	* tree-ssa-alias.c (ptr_deref_may_alias_decl_p): Use it
	to disambiguate marked decls and restrict pointers.

fortran/
	* trans.h (struct lang_type): Remove nontarget_type member.
	* trans.c (gfc_add_modify): Don't access it.
	* trans-decl.c (gfc_finish_var_decl): Don't allocate and set it,
	instead set DECL_RESTRICTED_P on affected decls.

testsuite/
	* gfortran.dg/pr41212.f90: New test.

From-SVN: r151761