Fix mi-nonstop.exp with extended-remote

Testing with "maint set target-non-stop on" makes mi-nonstop.exp run
with the extended-remote board.  That reveals that mi-nonstop.exp is
using the wrong predicate to check for "using remote protocol".

This is not visible today because non-stop tests all fail to run with
extended-remote board, because they spawn gdb and then do "set
non-stop on".  However, with that board, gdb connects to the gdbserver
from within mi_gdb_start, and changing non-stop when already connected
doesn't work.  Fix that by instead enabling non-stop mode on gdb's
command line.

gdb/testsuite/ChangeLog:
2015-11-30  Pedro Alves  <palves@redhat.com>

	* gdb.mi/mi-nonstop.exp: Append "set non-stop on" to GDBFLAGS
	instead of issuing "-gdb-set non-stop 1" after starting gdb.
	Use mi_is_target_remote instead of checking "is_remote target".
	* lib/gdb.exp (gdb_is_target_remote): Rename to ...
	(gdb_is_target_remote_prompt): ... this, and add 'prompt_regexp'
	parameter.
	(gdb_is_target_remote): Reimplement.
	* lib/mi-support.exp (mi_is_target_remote): New procedure.

gdb/ChangeLog

@@ -1,3 +1,14 @@
+2015-11-30  Pedro Alves  <palves@redhat.com>
+
+	* gdb.mi/mi-nonstop.exp: Append "set non-stop on" to GDBFLAGS
+	instead of issuing "-gdb-set non-stop 1" after starting gdb.
+	Use mi_is_target_remote instead of checking "is_remote target".
+	* lib/gdb.exp (gdb_is_target_remote): Rename to ...
+	(gdb_is_target_remote_prompt): ... this, and add 'prompt_regexp'
+	parameter.
+	(gdb_is_target_remote): Reimplement.
+	* lib/mi-support.exp (mi_is_target_remote): New procedure.
+
 2014-11-28  Pedro Alves  <palves@redhat.com>
 
 	* cp-name-parser.y (conversion_op): Use

gdb/testsuite/gdb.mi/mi-nonstop.exp

@@ -23,8 +23,12 @@ load_lib mi-support.exp
 set MIFLAGS "-i=mi"
 
 gdb_exit
-if {[mi_gdb_start]} {
-    continue
+
+save_vars { GDBFLAGS } {
+    append GDBFLAGS " -ex \"set non-stop on\""
+    if {[mi_gdb_start]} {
+	continue
+    }
 }
 
 proc mi_nonstop_resume { command test } {
@@ -49,7 +53,6 @@ if {[gdb_compile_pthreads "$srcdir/$subdir/$srcfile" $binfile executable $option
 mi_gdb_reinitialize_dir $srcdir/$subdir
 mi_gdb_load $binfile
 
-mi_gdb_test "-gdb-set non-stop 1" ".*"
 mi_gdb_test "-gdb-set mi-async 1" ".*"
 mi_detect_async
 
@@ -132,7 +135,7 @@ mi_gdb_test "-thread-select 2" "\\^done.*" "select first worker thread"
 mi_gdb_test "-gdb-set --thread 3 variable exit_first_thread=1" ".*\\^done" "ask the second thread to exit"
 
 set test "wait for thread exit"
-if { [is_remote target] } {
+if { [mi_is_target_remote] } {
     # The remote protocol doesn't have support for thread exit
     # notifications.
     unsupported $test

gdb/testsuite/lib/gdb.exp

@@ -3023,23 +3023,31 @@ proc skip_compile_feature_tests {} {
     return $result
 }
 
+# Helper for gdb_is_target_remote.  PROMPT_REGEXP is the expected
+# prompt.
+
+proc gdb_is_target_remote_prompt { prompt_regexp } {
+
+    set test "probe for target remote"
+    gdb_test_multiple "maint print target-stack" $test {
+	-re ".*emote serial target in gdb-specific protocol.*$prompt_regexp" {
+	    pass $test
+	    return 1
+	}
+	-re "$prompt_regexp" {
+	    pass $test
+	}
+    }
+    return 0
+}
+
 # Check whether we're testing with the remote or extended-remote
 # targets.
 
 proc gdb_is_target_remote {} {
     global gdb_prompt
 
-    set test "probe for target remote"
-    gdb_test_multiple "maint print target-stack" $test {
-	-re ".*emote serial target in gdb-specific protocol.*$gdb_prompt $" {
-	    pass $test
-	    return 1
-	}
-	-re "$gdb_prompt $" {
-	    pass $test
-	}
-    }
-    return 0
+    return [gdb_is_target_remote_prompt "$gdb_prompt $"]
 }
 
 # Return 1 if the current remote target is an instance of our GDBserver, 0

gdb/testsuite/lib/mi-support.exp

@@ -2499,3 +2499,12 @@ proc mi_skip_python_tests {} {
     global mi_gdb_prompt
     return [skip_python_tests_prompt "$mi_gdb_prompt$"]
 }
+
+# Check whether we're testing with the remote or extended-remote
+# targets.
+
+proc mi_is_target_remote {} {
+    global mi_gdb_prompt
+
+    return [gdb_is_target_remote_prompt "$mi_gdb_prompt"]
+}