Fix posix/tst-regex by using a dedicated input-file.

The recent commit e6855a3bdf
changed the encoding of ChangeLog.old/ChangeLog.8 from ISO-8859 to UTF-8.
Unfortunately the test posix/tst-regex assumes the former encoding.
Furthermore Francesco Potortì is now written with 'ì' instead of 'i`'
which would lead to two further matches in the first call to test_expr.

This patch just copies the former ChangeLog.8 file to tst-regex.input
and adjusts the test in order to use this new input file.

ChangeLog:

	* posix/tst-regex.c (do_test): Use tst-regex.input as input file.
	* posix/tst-regex.input: New file.

ChangeLog

@@ -1,3 +1,8 @@
+2019-08-28  Stefan Liebler  <stli@linux.ibm.com>
+
+	* posix/tst-regex.c (do_test): Use tst-regex.input as input file.
+	* posix/tst-regex.input: New file.
+
 2019-08-23  Mihailo Stojanovic  <mihailo.stojanovic@rt-rk.com>
 
 	[BZ #24916]

posix/tst-regex.c

@@ -67,7 +67,7 @@ do_test (void)
   mtrace ();
 
   /* Make the content of the file available in memory.  */
-  file = "../ChangeLog.old/ChangeLog.8";
+  file = "./tst-regex.input";
   fd = open (file, O_RDONLY);
   if (fd == -1)
     error (EXIT_FAILURE, errno, "cannot open %s", basename (file));