Add "new-ui console" tests

This adds a test that uses new-ui to create a secondary console, and
then runs some basic smoke tests.  It ensures that:

 - synchronous commands send output to the UI that initiated it

 - asynchronous events like breakpoint hits are reported on all
   consoles.

 - "new-ui" without arguments doesn't crash.

 - The "new-ui" command doesn't repeat.

gdb/testsuite/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* gdb.base/new-ui.exp: New file.
	* lib/mi-support.exp (switch_gdb_spawn_id): Move to ...
	* lib/gdb.exp (switch_gdb_spawn_id): ... here.
	(with_spawn_id): New procedure.

2 files changed, 32 insertions, 12 deletions

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 878da16..b52fdd9 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -2075,6 +2075,38 @@ proc with_target_charset { target_charset body } {
     }
 }
 
+# Switch the default spawn id to SPAWN_ID, so that gdb_test,
+# mi_gdb_test etc. default to using it.
+
+proc switch_gdb_spawn_id {spawn_id} {
+    global gdb_spawn_id
+    global board board_info
+
+    set gdb_spawn_id $spawn_id
+    set board [host_info name]
+    set board_info($board,fileid) $spawn_id
+}
+
+# Run BODY with SPAWN_ID as current spawn id.
+
+proc with_spawn_id { spawn_id body } {
+    global gdb_spawn_id
+
+    set saved_spawn_id $gdb_spawn_id
+    switch_gdb_spawn_id $spawn_id
+
+    set code [catch {uplevel 1 $body} result]
+
+    switch_gdb_spawn_id $saved_spawn_id
+
+    if {$code == 1} {
+	global errorInfo errorCode
+	return -code $code -errorinfo $errorInfo -errorcode $errorCode $result
+    } else {
+	return -code $code $result
+    }
+}
+
 # Select the largest timeout from all the timeouts:
 # - the local "timeout" variable of the scope two levels above,
 # - the global "timeout" variable,
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index edfc07d..7b5c90b 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -122,18 +122,6 @@ proc mi_create_inferior_pty {} {
     }
 }
 
-# Switch the default spawn id to SPAWN_ID, so that mi_gdb_test
-# etc. default to using it.
-
-proc switch_gdb_spawn_id {spawn_id} {
-    global gdb_spawn_id
-    global board board_info
-
-    set gdb_spawn_id $spawn_id
-    set board [host_info name]
-    set board_info($board,fileid) $spawn_id
-}
-
 proc mi_gdb_start_separate_mi_tty { args } {
     global gdb_prompt mi_gdb_prompt
     global timeout