make dprintf.exp pass in target async mode

When target-async is enabled, dprintf.exp fails:

 Running ../../../src/gdb/testsuite/gdb.base/dprintf.exp ...
 FAIL: gdb.base/dprintf.exp: 1st dprintf, call
 FAIL: gdb.base/dprintf.exp: 2nd dprintf, call
 FAIL: gdb.base/dprintf.exp: Set dprintf function
 FAIL: gdb.base/dprintf.exp: 1st dprintf, fprintf
 FAIL: gdb.base/dprintf.exp: 2nd dprintf, fprintf

 Breakpoint 2, main (argc=1, argv=0x7fffffffd3f8) at ../../../src/gdb/testsuite/gdb.base/dprintf.c:33
 33        int loc = 1234;
 (gdb) continue
 Continuing.
 kickoff 1234
 also to stderr 1234
 At foo entry
 (gdb) FAIL: gdb.base/dprintf.exp: 1st dprintf, call

The problem is that GDB gave the prompt back to the user too early.

This happens when calling functions while handling an event that
doesn't cause a user visible stop.  dprintf with "set dprintf-style
gdb" is one such case.  This patch adds a test case that has a
breakpoint with a condition that calls a function that returns false,
so that regression testing isn't dependent on the implementation of
dprintf.

The problem happens because run_inferior_call causes GDB to forget
that it is running in sync_execution mode, so any event that runs an
inferior call causes fetch_inferior_event to display the prompt, even
if the event should not result in a user visible stop (that is, gdb
resumes the inferior and waits for the next event).

This patch fixes the issue by noticing when GDB was in sync_execution
mode in run_inferior_call, and taking care to restore this state
afterward.

gdb/
2014-03-20  Tom Tromey  <tromey@redhat.com>

	PR cli/15718
	* infcall.c: Include event-top.h.
	(run_inferior_call): Call async_disable_stdin if needed.

gdb/testsuite/
2014-03-20  Tom Tromey  <tromey@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	PR cli/15718
	* gdb.base/condbreak-call-false.c: New file.
	* gdb.base/condbreak-call-false.exp: New file.

1 files changed, 39 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/condbreak-call-false.c b/gdb/testsuite/gdb.base/condbreak-call-false.c
new file mode 100644
index 0000000..ed9a3f4
--- /dev/null
+++ b/gdb/testsuite/gdb.base/condbreak-call-false.c
@@ -0,0 +1,39 @@
+/* Copyright 2013-2014 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/>.  */
+
+int
+zero (void)
+{
+  return 0;
+}
+
+int
+foo (void)
+{
+  return 23;
+}
+
+void
+bar (void)
+{
+}
+
+
+int
+main (void)
+{
+  foo ();
+  bar ();
+}