Fix "set debug timestamp"

PR cli/29945 points out that "set debug timestamp 1" stopped working
-- this is a regression due to commit b8043d27 ("Remove a ui-related
memory leak").

This patch fixes the bug and adds a regression test.

I think this should probably be backported to the gdb 13 branch.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29945

gdb/testsuite/gdb.base/timestamp.exp

@@ -0,0 +1,24 @@
+# Copyright 2022 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test that timestamps are printed when logging.
+
+clean_restart
+
+# This is a simple way to get logging output.
+gdb_test_no_output "set debug expression 1"
+gdb_test_no_output "set debug timestamp 1"
+
+gdb_test "print 23" "\[0-9\]+\\.\[0-9\]+ Operation: OP_LONG.* = 23"

gdb/top.c

@@ -305,7 +305,7 @@ ui::ui (FILE *instream_, FILE *outstream_, FILE *errstream_)
     m_gdb_stdout (new pager_file (new stdio_file (outstream))),
     m_gdb_stdin (new stdio_file (instream)),
     m_gdb_stderr (new stderr_file (errstream)),
-    m_gdb_stdlog (m_gdb_stderr)
+    m_gdb_stdlog (new timestamped_file (m_gdb_stderr))
 {
   unbuffer_stream (instream_);