Fix djgpp gdb build

- 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.

gdb/ChangeLog

@@ -1,3 +1,14 @@
+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.
+
 2016-07-21  Pedro Alves  <palves@redhat.com>
 
 	* windows-nat.c (handle_exception): Remove "th".

gdb/go32-nat.c

@@ -677,7 +677,7 @@ go32_create_inferior (struct target_ops *ops, char *exec_file,
   if (cmdlen > 1024*1024)
     error (_("Command line too long."));
 
-  cmdline = xmalloc (cmdlen + 4);
+  cmdline = (char *) xmalloc (cmdlen + 4);
   strcpy (cmdline + 1, args);
   /* If the command-line length fits into DOS 126-char limits, use the
      DOS command tail format; otherwise, tell v2loadimage to pass it

gdb/ser-go32.c

@@ -593,9 +593,26 @@ dos_close (struct serial *scb)
 }
 
 
+/* Implementation of the serial_ops flush_output method.  */
 
 static int
-dos_noop (struct serial *scb)
+dos_flush_output (struct serial *scb)
+{
+  return 0;
+}
+
+/* Implementation of the serial_ops setparity method.  */
+
+static int
+dos_setparity (struct serial *scb, int parity)
+{
+  return 0;
+}
+
+/* Implementation of the serial_ops drain_output method.  */
+
+static int
+dos_drain_output (struct serial *scb)
 {
   return 0;
 }
@@ -792,7 +809,7 @@ dos_write (struct serial *scb, const void *buf, size_t count)
   size_t fifosize = port->fifo ? 16 : 1;
   long then;
   size_t cnt;
-  const char *str = buf;
+  const char *str = (const char *) buf;
 
   while (count > 0)
     {
@@ -857,7 +874,7 @@ static const struct serial_ops dos_ops =
   NULL,				/* fdopen, not implemented */
   dos_readchar,
   dos_write,
-  dos_noop,			/* flush output */
+  dos_flush_output,
   dos_flush_input,
   dos_sendbreak,
   dos_raw,
@@ -868,8 +885,8 @@ static const struct serial_ops dos_ops =
   dos_noflush_set_tty_state,
   dos_setbaudrate,
   dos_setstopbits,
-  dos_noop,
-  dos_noop,			/* Wait for output to drain.  */
+  dos_setparity,
+  dos_drain_output,
   (void (*)(struct serial *, int))NULL	/* Change into async mode.  */
 };
 

gdb/top.c

@@ -470,7 +470,7 @@ void (*pre_init_ui_hook) (void);
 static void
 do_chdir_cleanup (void *old_dir)
 {
-  chdir (old_dir);
+  chdir ((const char *) old_dir);
   xfree (old_dir);
 }
 #endif