printf implementation: add missing const to padding strings.

Change-Id: Ic104359e2220a717d8f6257ba86775905d81384d
diff --git a/libc/stdio/vfwprintf.cpp b/libc/stdio/vfwprintf.cpp
index 72f973c..89e889e 100644
--- a/libc/stdio/vfwprintf.cpp
+++ b/libc/stdio/vfwprintf.cpp
@@ -128,10 +128,10 @@
    * below longer.
    */
 #define PADSIZE 16 /* pad chunk size */
-  static CHAR_TYPE blanks[PADSIZE] = {
+  static const CHAR_TYPE blanks[PADSIZE] = {
     ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '
   };
-  static CHAR_TYPE zeroes[PADSIZE] = {
+  static const CHAR_TYPE zeroes[PADSIZE] = {
     '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0'
   };