[PATCH] Fix djgpp gdb build

[Eli Zaretskii]

> From: Pedro Alves <palves@redhat.com>
> Date: Thu, 21 Jul 2016 13:26:30 +0100
> 
>  - A few missing casts required by C++, resulting in:
> 
>    ../../src/gdb/ser-go32.c:795:21: error: invalid conversion from 'const void*' to 'const char*' [-fpermissive]
> 
>    etc.
> 
>  - dos_noop has an incompatible prototype with struct serial_ops's
>    setparity, resulting in:
> 
>     ../../src/gdb/ser-go32.c:874:1: error: invalid conversion from 'int (*)(serial*)' to 'int (*)(serial*, int)' [-fpermissive]
> 
>    (I thought of calling the ser-base.c default methods, but djgpp
>    doesn't include ser-base.c in the build.)
> 
> gdb/ChangeLog:
> 2016-07-21  Pedro Alves  <palves@redhat.com>
> 
> 	* go32-nat.c (go32_create_inferior): Add cast.
> 	* ser-go32.c (dos_noop): Delete.
> 	(dos_flush_output, dos_setparity, dos_drain_output): New
> 	functions.
> 	(dos_write): Add cast.
> 	(dos_ops): Use dos_flush_output, dos_setparity and
> 	dos_drain_output.
> 	* top.c (do_chdir_cleanup): Add cast.

OK.  Thanks for taking care of this port.