flex 2.5.31 filter.c bug and patch

[Bruce Lilly]

On some systems filter.c fails to compile because stdin and stdout are
never guaranteed to be lvalues (see ANSI C), but filter.c expects them
them to be lvalues:

filter.c(161) : error C2106: '=' : left operand must be l-value
filter.c(163) : error C2106: '=' : left operand must be l-value
filter.c(184) : error C2106: '=' : left operand must be l-value

A patch is attached.

*** filter.c.orig       Tue Mar 25 11:39:08 2003
--- filter.c    Wed Apr 16 15:45:00 2003
***************
*** 158,166 ****
                        int     r;
  
                        /* setup streams again */
!                       if ((stdin = fdopen (0, "r")) == NULL)
                                flexfatal (_("fdopen(0) failed"));
!                       if ((stdout = fdopen (1, "w")) == NULL)
                                flexfatal (_("fdopen(1) failed"));
  
                        if ((r = chain->filter_func (chain)) == -1)
--- 158,166 ----
                        int     r;
  
                        /* setup streams again */
!                       if (fdopen (0, "r") == NULL)
                                flexfatal (_("fdopen(0) failed"));
!                       if (fdopen (1, "w") == NULL)
                                flexfatal (_("fdopen(1) failed"));
  
                        if ((r = chain->filter_func (chain)) == -1)
***************
*** 181,187 ****
        if (dup2 (pipes[1], 1) == -1)
                flexfatal (_("dup2(pipes[1],1)"));
        close (pipes[1]);
!       if ((stdout = fdopen (1, "w")) == NULL)
                flexfatal (_("fdopen(1) failed"));
  
        return true;
--- 181,187 ----
        if (dup2 (pipes[1], 1) == -1)
                flexfatal (_("dup2(pipes[1],1)"));
        close (pipes[1]);
!       if (fdopen (1, "w") == NULL)
                flexfatal (_("fdopen(1) failed"));
  
        return true;