PATCH: fix a comment typo in c-format.c

[Ben Elliston]

Committed as obvious:

2009-05-22  Ben Elliston  <bje@au.ibm.com>

        * c-format.c (handle_format_attribute): Fix comment typo.

Index: c-format.c
===================================================================
--- c-format.c  (revision 147783)
+++ c-format.c  (working copy)
@@ -2865,7 +2865,7 @@ handle_format_attribute (tree *node, tre
     }
 
   /* If this is a custom GCC-internal format type, we have to
-     initialize certain bits a runtime.  */
+     initialize certain bits at runtime.  */
   if (info.format_type == asm_fprintf_format_type
       || info.format_type == gcc_gfc_format_type
       || info.format_type == gcc_diag_format_type