Use filtered output in language_info

Change language_info to use filtered output.  This is ok because the
sole caller uses filtered output elsewhere, and because this function
calls show_language_command, which also uses filtered output.

gdb/language.c

diff --git a/gdb/language.c b/gdb/language.c
index 132ff76..0e6a1a4 100644
--- a/gdb/language.c
+++ b/gdb/language.c
@@ -383,7 +383,7 @@ language_info ()
     return;
 
   expected_language = current_language;
-  printf_unfiltered (_("Current language:  %s\n"), language);
+  printf_filtered (_("Current language:  %s\n"), language);
   show_language_command (NULL, 1, NULL, NULL);
 }