Enable gdb.threads/non-ldr-exc-*.exp on is_remote target boards

This commit makes the gdb.threads/non-ldr-exc-*.exp tests run (and
pass) with --target_board=native-gdbserver.

(These tests were already running with
--target_board=native-extended-gdbserver, because that board is not
is_remote.)

The "No exec event support in the remote protocol." comment is stale.
It's actually supported.

gdb/ChangeLog:
2017-10-12  Pedro Alves  <palves@redhat.com>

	* gdb.threads/non-ldr-exc-1.exp: No longer skip if is_remote target.
	* gdb.threads/non-ldr-exc-2.exp: Ditto.
	* gdb.threads/non-ldr-exc-3.exp: Ditto.
	* gdb.threads/non-ldr-exc-4.exp: Ditto.

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2017-10-12  Pedro Alves  <palves@redhat.com>
+
+	* gdb.threads/non-ldr-exc-1.exp: No longer skip if is_remote target.
+	* gdb.threads/non-ldr-exc-2.exp: Ditto.
+	* gdb.threads/non-ldr-exc-3.exp: Ditto.
+	* gdb.threads/non-ldr-exc-4.exp: Ditto.
+
 2017-10-11  Anton Kolesov  <Anton.Kolesov@synopsys.com>
 
 	* gdb.arch/arc-tdesc-cpu.exp: New file.

gdb/testsuite/gdb.threads/non-ldr-exc-1.exp

@@ -16,11 +16,6 @@
 # Test that when a thread other than the main thread execs, we follow
 # through to the new incarnation of the main thread.
 
-# No exec event support in the remote protocol.
-if { [is_remote target] } then {
-    continue
-}
-
 standard_testfile
 set executable ${testfile}
 

gdb/testsuite/gdb.threads/non-ldr-exc-2.exp

@@ -17,11 +17,6 @@
 # through to the new incarnation of the main thread, even if the main
 # thread had already exited before the exec.
 
-# No exec event support in the remote protocol.
-if { [is_remote target] } then {
-    continue
-}
-
 standard_testfile
 set executable ${testfile}
 

gdb/testsuite/gdb.threads/non-ldr-exc-3.exp

@@ -19,11 +19,6 @@
 # non-ldr-exc-2.exp in that we have more than two threads in the
 # program when the exec happens.
 
-# No exec event support in the remote protocol.
-if { [is_remote target] } then {
-    continue
-}
-
 standard_testfile
 set executable ${testfile}
 

gdb/testsuite/gdb.threads/non-ldr-exc-4.exp

@@ -18,11 +18,6 @@
 # from non-ldr-exc-1.exp in that we have more than two threads in the
 # program when the exec happens.
 
-# No exec event support in the remote protocol.
-if { [is_remote target] } then {
-    continue
-}
-
 standard_testfile
 set executable ${testfile}