[binutils-gdb] Remove cleanup from ada-lang.c

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 6f46ac8531ead61003c96b8e2fa6a383ea8d8c58 ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: 6f46ac8531ead61003c96b8e2fa6a383ea8d8c58

Remove cleanup from ada-lang.c

This removes a cleanup from ada-lang.c by having
ada_exception_message_1 return a unique_xmalloc_ptr.

ChangeLog
2018-05-21  Tom Tromey  <tom@tromey.com>

	* ada-lang.c (ada_exception_message_1, ada_exception_message):
	Return unique_xmalloc_ptr.
	(print_it_exception): Update.