Introduce target_is_gdbserver

This patch introduces a function in gdbserver-support.exp to find out
whether the current target is GDBserver.

The code was inspired from gdb.trace/qtro.exp, so it replaces the code
there by a call to the new function.

gdb/testsuite/ChangeLog:

	* gdb.trace/qtro.exp: Replace gdbserver detection code by...
	* lib/gdb.exp (target_is_gdbserver): New
	procedure.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-12-10  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* gdb.trace/qtro.exp: Replace gdbserver detection code by...
+	* lib/gdb.exp (target_is_gdbserver): New procedure.
+
 2014-12-08  Doug Evans  <dje@google.com>
 
 	* gdb.python/py-objfile.exp: Add tests for objfile.owner.

gdb/testsuite/gdb.trace/qtro.exp

@@ -98,18 +98,7 @@ if { $traceframe_info_supported == -1 } {
 }
 
 # Check whether we're testing with our own GDBserver.
-set is_gdbserver -1
-set test "probe for GDBserver"
-gdb_test_multiple "monitor help" $test {
-    -re "The following monitor commands are supported.*debug-hw-points.*remote-debug.*GDBserver.*$gdb_prompt $" {
-	set is_gdbserver 1
-	pass $test
-    }
-    -re "$gdb_prompt $" {
-	set is_gdbserver 0
-	pass $test
-    }
-}
+set is_gdbserver [target_is_gdbserver]
 if { $is_gdbserver == -1 } {
     return -1
 }

gdb/testsuite/lib/gdb.exp

@@ -2537,6 +2537,31 @@ proc gdb_is_target_remote {} {
     return 0
 }
 
+# Return 1 if the current remote target is an instance of our GDBserver, 0
+# otherwise.  Return -1 if there was an error and we can't tell.
+
+gdb_caching_proc target_is_gdbserver {
+    global gdb_prompt
+
+    set is_gdbserver -1
+    set test "Probing for GDBserver"
+
+    gdb_test_multiple "monitor help" $test {
+	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
+	    set is_gdbserver 1
+	}
+	-re "$gdb_prompt $" {
+	    set is_gdbserver 0
+	}
+    }
+
+    if { $is_gdbserver == -1 } {
+	verbose -log "Unable to tell whether we are using GDBserver or not."
+    }
+
+    return $is_gdbserver
+}
+
 set compiler_info		"unknown"
 set gcc_compiled		0
 set hp_cc_compiler		0