Fix warnings that would be caused by gcc flag -Wwrite-strings

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5206 c046a42c-6fe2-441c-8c8c-71466251a162

gdbstub.h

diff --git a/gdbstub.h b/gdbstub.h
index e1c9efb..ba65f93 100644
--- a/gdbstub.h
+++ b/gdbstub.h
@@ -6,7 +6,7 @@
 typedef void (*gdb_syscall_complete_cb)(CPUState *env,
                                         target_ulong ret, target_ulong err);
 
-void gdb_do_syscall(gdb_syscall_complete_cb cb, char *fmt, ...);
+void gdb_do_syscall(gdb_syscall_complete_cb cb, const char *fmt, ...);
 int use_gdb_syscalls(void);
 #ifdef CONFIG_USER_ONLY
 int gdb_handlesig (CPUState *, int);