fix PR 17106

This fixes PR 17106, a regression in printing.

The bug is that resolve_dynamic_type follows struct members and
references, but doesn't consider the possibility of infinite
recursion.

This patch fixes the problem by limiting reference following to the
topmost layer of calls -- that is, reference-typed struct members are
never considered as being VLAs.

Built and regtested on x86-64 Fedora 20.
New test case included.

2014-07-14  Tom Tromey  <tromey@redhat.com>

	PR exp/17106:
	* gdbtypes.c (is_dynamic_type_internal): New function, from
	is_dynamic_type.
	(is_dynamic_type): Rewrite.
	(resolve_dynamic_union): Use resolve_dynamic_type_internal.
	(resolve_dynamic_struct): Likewise.
	(resolve_dynamic_type_internal): New function, from
	resolve_dynamic_type.
	(resolve_dynamic_type): Rewrite.

2014-07-14  Tom Tromey  <tromey@redhat.com>

	* gdb.cp/vla-cxx.cc: New file.
	* gdb.cp/vla-cxx.exp: New file.