libstdc++: Use dg-additional-files in some non-I/O tests

libstdc++: Use dg-additional-files in some non-I/O tests

libstdc++-v3/ChangeLog:

	* testsuite/20_util/hash/chi2_q_document_words.cc: Use
	dg-additional-files for input text.
	* testsuite/performance/ext/pb_ds/all_text_find.cc: Likewise.
	* testsuite/performance/ext/pb_ds/multimap_text_find.hpp:
	Likewise.
	* testsuite/performance/ext/pb_ds/multimap_text_insert.hpp:
	Likewise.
	* testsuite/performance/ext/pb_ds/multimap_text_insert_mem.hpp:
	Likewise.
	* testsuite/performance/ext/pb_ds/priority_queue_text_join.cc:
	Likewise.
	* testsuite/performance/ext/pb_ds/priority_queue_text_modify.hpp: Likewise.
	* testsuite/performance/ext/pb_ds/priority_queue_text_pop_mem.cc: Likewise.
	* testsuite/performance/ext/pb_ds/priority_queue_text_push.cc:
	Likewise.
	* testsuite/performance/ext/pb_ds/priority_queue_text_push_pop.cc: Likewise.
	* testsuite/performance/ext/pb_ds/tree_text_insert.cc: Likewise.
	* testsuite/performance/ext/pb_ds/tree_text_lor_find.cc:
	Likewise.