Add additional_sources_used

Add additional_sources_used

2015-02-24  Tom de Vries  <tom@codesourcery.com>

	PR testsuite/65126
	* lib/gcc-defs.exp (additional_sources_used): Add new var.
	(dg-additional-files-options): Copy additional_sources to
	additional_sources_used before emptying additional_sources.
	* lib/gcc-dg.exp (cleanup-coverage-files, cleanup-repo-files)
	(cleanup-stack-usage, cleanup-ada-spec, cleanup-dump)
	(cleanup-saved-temps): Use additional_sources_used instead of
	additional_sources.
	(dg-test): Reset additional_sources_used.

From-SVN: r220929