Throughout change TTY_* to PTY_*, tty_* to pty_*, and ttym_* to ptmx_*.

* devices.cc: Regenerate.
* dtable.cc: (fh_alloc): Preserve /dev/tty name when that's what we opened.
(build_fh_pc): Preserve any existing name.
* fhandler.cc (fhandler_base::open_with_arch): Ditto.
* fhandler_tty.cc (fhandler_pty_master::fhandler_pty_master): Force the name to
/dev/ptmx while preserving other pty master device information.
* path.h (cfree_maybe): New macro.
(path_conv::operator =): Free any allocated strings in target.
(path_conv::free_strings): Delete unused function.
* sigproc.cc (proc_terminate): Remove previous accommodation for execed
processes since it didn't have the desired effect.  Change comment to a FIXME.
* spawn.cc (chExeced): Mark NO_COPY.
(exe_suffixes): Ditto.

winsup/cygwin/sigproc.cc

@@ -374,14 +374,13 @@ proc_terminate ()
       int i;
       for (i = 0; i < nprocs; i++)
 	{
-	  extern child_info_spawn *chExeced;
-	  /* Don't reset the ppid to 1 if this pid is still going to be
-	     associated with a process.
-	     FIXME: The problem with this simplistic approach is that the
-	     ppid for any surviving children will never be set to 1 in
-	     this scenario.  A potential fix would be to move procs into
-	     cygheap but that would complicate startup.  What else is new? */
-	  if (!chExeced)
+	  /* FIXME: Resetting the ppid to 1 when this process execs is decidedly
+	     non-UNIXy.  We should, at the very least, keep a list of pids
+	     for the exec process to reset when *it* exits.  However, avoiding
+	     setting ppid when we are exec'ing causes the ppid to *never* be
+	     set to 1 so we don't do that either.
+	  if (!hExeced)
+	     */
 	    procs[i]->ppid = 1;
 	  if (procs[i].wait_thread)
 	    {