Preserve TREE_THIS_NOTRAP during inlining in more cases

Preserve TREE_THIS_NOTRAP during inlining in more cases

For parameters passed by reference, the Ada compiler sets TREE_THIS_NOTRAP
on their dereference to prevent tree_could_trap_p from returning true and
then causing a new basic block to be created for every access to them,
given that in Ada the -fnon-call-exceptions flag is enabled by default.

However, when the subprogram is inlined, this TREE_THIS_NOTRAP flag cannot
be blindly preserved because the call may pass the dereference of a pointer
as the argument: even if the compiler generates a check that the pointer is
not null just before, preserving TREE_THIS_NOTRAP could cause an access to
be hoisted before the check; therefore it gets cleared for parameters.

Now that's suboptimal if the argument is a full object because accessing it
through the dereference of the parameter cannot trap, which causes MEM_REFs
of the form MEM_REF [&DECL] to be considered as trapping in the case where
the nominal subtype of DECL is self-referential.

gcc/
	* tree-inline.cc (maybe_copy_this_notrap): New function.  Also copy
	the TREE_THIS_NOTRAP flag for parameters when the argument is a full
	object and the parameter's type is self-referential.
	(remap_gimple_op_r): Call maybe_copy_this_notrap.
	(copy_tree_body_r): Likewise.