convert to_thread_address_space to use TARGET_DEFAULT_FUNC

convert to_thread_address_space to use TARGET_DEFAULT_FUNC

This converts to_thread_address_space to use TARGET_DEFAULT_FUNC.

This method was one of a handful not using the normal target
delegation approach.  The only rationale here is consistency in the
target vector.

Built and regtested on x86-64 Fedora 20.

2014-06-04  Tom Tromey  <tromey@redhat.com>

	* target-delegates.c: Rebuild.
	* target.c (default_thread_address_space): New function.
	(target_thread_address_space): Simplify.
	* target.h (struct target_ops) <to_thread_address_space>: Add
	TARGET_DEFAULT_FUNC.