Remove extra '.' from error message

A local gdb test failed with this error message:

 Remote communication error.  Target disconnected.: Arg list too long.

The ".:" seemed weird to me.  This patch removes the ".".

Reviewed-by: John Baldwin <jhb@FreeBSD.org>

gdb/remote.c

@@ -9648,7 +9648,7 @@ remote_target::readchar (int timeout)
       /* no return */
     case SERIAL_ERROR:
       unpush_and_perror (this, _("Remote communication error.  "
-				 "Target disconnected."));
+				 "Target disconnected"));
       /* no return */
     case SERIAL_TIMEOUT:
       break;
@@ -9677,7 +9677,7 @@ remote_target::remote_serial_write (const char *str, int len)
   if (serial_write (rs->remote_desc, str, len))
     {
       unpush_and_perror (this, _("Remote communication error.  "
-				 "Target disconnected."));
+				 "Target disconnected"));
     }
 
   if (rs->got_ctrlc_during_io)

gdb/testsuite/gdb.server/server-kill.exp

@@ -97,7 +97,7 @@ proc_with_prefix test_tstatus {} {
 
     # Force GDB to talk with GDBserver, so that we can get the
     # "connection closed" error.
-    gdb_test "tstatus" {Remote connection closed|Remote communication error\.  Target disconnected\.: Connection reset by peer\.}
+    gdb_test "tstatus" {Remote connection closed|Remote communication error\.  Target disconnected: Connection reset by peer\.}
 }
 
 # Test unwinding with no debug/unwind info, right after the connection