gdb: make deprecated_show_value_hack static

The deprecated_show_value_hack function is now only used inside
cli-setshow.c, so lets make the function static to discourage its use
anywhere else.

There should be no user visible changes after this commit

Reviewed-By: Tom Tromey <tom@tromey.com>
diff --git a/gdb/cli/cli-setshow.c b/gdb/cli/cli-setshow.c
index dad3e60..07233e3 100644
--- a/gdb/cli/cli-setshow.c
+++ b/gdb/cli/cli-setshow.c
@@ -117,7 +117,7 @@ parse_cli_boolean_value (const char *arg)
 }
 
 
-void
+static void
 deprecated_show_value_hack (struct ui_file *ignore_file,
 			    int ignore_from_tty,
 			    struct cmd_list_element *c,
diff --git a/gdb/command.h b/gdb/command.h
index e9c9f16..a4641bb 100644
--- a/gdb/command.h
+++ b/gdb/command.h
@@ -656,16 +656,11 @@ extern void complete_on_enum (completion_tracker &tracker,
 extern void help_list (struct cmd_list_element *, const char *,
 		       enum command_class, struct ui_file *);
 
-/* Method for show a set/show variable's VALUE on FILE.  If this
-   method isn't supplied deprecated_show_value_hack() is called (which
-   is not good).  */
+/* Method for show a set/show variable's VALUE on FILE.  */
 typedef void (show_value_ftype) (struct ui_file *file,
 				 int from_tty,
 				 struct cmd_list_element *cmd,
 				 const char *value);
-/* NOTE: i18n: This function is not i18n friendly.  Callers should
-   instead print the value out directly.  */
-extern show_value_ftype deprecated_show_value_hack;
 
 /* Various sets of extra literals accepted.  */
 extern const literal_def integer_unlimited_literals[];