infcmd.c: Remove stale TODO

This TODO has been stale for over 2 years.  In bd5635a1 (1991), we
already see the comment, when we only had a bare attach_command:

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /*
  * TODO:
  * Should save/restore the tty state since it might be that the
  * program to be debugged was started on this tty and it wants
  * the tty in some state other than what we want.  If it's running
  * on another terminal or without a terminal, then saving and
  * restoring the tty state is a harmless no-op.
  * This only needs to be done if we are attaching to a process.
  */

 /*
  * attach_command --
  * takes a program started up outside of gdb and ``attaches'' to it.
  * This stops it cold in its tracks and allows us to start tracing it.
  * For this to work, we must be able to send the process a
  * signal and we must have the same effective uid as the program.
  */
 void
 attach_command (args, from_tty)
      char *args;
      int from_tty;
 {
   target_attach (args, from_tty);
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Later in b5a3d2aa (1992) target_terminal_init, etc. calls are added to
attach_command, and in 7e97eb28 (1992) we see:

+      /* If we attached to the process, we might or might not be sharing
+        a terminal.  Avoid printing error msg if we are unable to set our
+        terminal's process group to his process group ID.  */
+      if (!attach_flag) {
+       OOPSY ("ioctl TIOCSPGRP");

Clearly the TODO has been stale for a long while.

I considered preserving the text elsewhere, but then thought the
comments in inflow.c already have all the necessary info.

gdb/ChangeLog:

	* infcmd.c (attach_command): Remove comment.

gdb/infcmd.c

@@ -2365,16 +2365,6 @@ proceed_after_attach (int pid)
   do_cleanups (old_chain);
 }
 
-/*
- * TODO:
- * Should save/restore the tty state since it might be that the
- * program to be debugged was started on this tty and it wants
- * the tty in some state other than what we want.  If it's running
- * on another terminal or without a terminal, then saving and
- * restoring the tty state is a harmless no-op.
- * This only needs to be done if we are attaching to a process.
- */
-
 /* attach_command --
    takes a program started up outside of gdb and ``attaches'' to it.
    This stops it cold in its tracks and allows us to start debugging it.