[obv] unbreak the build on DJGPP.

[Yao Qi]

Hi,
This patch unbreaks the build failure when I cross compile GDB for
i586-pc-msdosdjgpp host and target on Linux.  I'll apply it.

gdb:

2012-07-30  Yao Qi  <yao@codesourcery.com>

	* go32-nat.c: Declare _initialize_go32_nat.
	* ser-go32.c: Declare _initialize_ser_dos.
	* top.c (do_chdir_cleanup): Add 'static'.
---
 gdb/go32-nat.c |    3 +++
 gdb/ser-go32.c |    2 ++
 gdb/top.c      |    2 +-
 3 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/gdb/go32-nat.c b/gdb/go32-nat.c
index b8fe284..d848017 100644
--- a/gdb/go32-nat.c
+++ b/gdb/go32-nat.c
@@ -2097,6 +2097,9 @@ go32_info_dos_command (char *args, int from_tty)
   help_list (info_dos_cmdlist, "info dos ", class_info, gdb_stdout);
 }
 
+/* -Wmissing-prototypes */
+extern initialize_file_ftype _initialize_go32_nat;
+
 void
 _initialize_go32_nat (void)
 {
diff --git a/gdb/ser-go32.c b/gdb/ser-go32.c
index 84f449a..0c13d20 100644
--- a/gdb/ser-go32.c
+++ b/gdb/ser-go32.c
@@ -909,6 +909,8 @@ dos_info (char *arg, int from_tty)
 #endif
 }
 
+/* -Wmissing-prototypes */
+extern initialize_file_ftype _initialize_ser_dos;
 
 void
 _initialize_ser_dos (void)
diff --git a/gdb/top.c b/gdb/top.c
index bbbd799..cb30c8b 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -336,7 +336,7 @@ read_command_file (FILE *stream)
 void (*pre_init_ui_hook) (void);
 
 #ifdef __MSDOS__
-void
+static void
 do_chdir_cleanup (void *old_dir)
 {
   chdir (old_dir);
-- 
1.7.7.6