Fix buffer overflow processing long words in Mangle().

Patch adpated from upstream commit, omitting changes to 'NEWS':

https://github.com/cracklib/cracklib/commit/33d7fa4585247cd2247a1ffa032ad245836c6edb

From 33d7fa4585247cd2247a1ffa032ad245836c6edb Mon Sep 17 00:00:00 2001
From: Jan Dittberner <jan@dittberner.info>
Date: Thu, 25 Aug 2016 17:17:53 +0200
Subject: [PATCH] Fix a buffer overflow processing long words

A buffer overflow processing long words has been discovered. This commit
applies the patch from
https://build.opensuse.org/package/view_file/Base:System/cracklib/0004-overflow-processing-long-words.patch
by Howard Guo.

See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=835386 and
http://www.openwall.com/lists/oss-security/2016/08/23/8
---
 src/NEWS        | 1 +
 src/lib/rules.c | 5 ++---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib/rules.c b/src/lib/rules.c
index d193cc0..3a2aa46 100644
--- a/lib/rules.c
+++ b/lib/rules.c
@@ -434,9 +434,8 @@ Mangle(input, control)		/* returns a pointer to a controlled Mangle */
 {
     int limit;
     register char *ptr;
-    static char area[STRINGSIZE];
-    char area2[STRINGSIZE];
-    area[0] = '\0';
+    static char area[STRINGSIZE * 2] = {0};
+    char area2[STRINGSIZE * 2] = {0};
     strcpy(area, input);
 
     for (ptr = control; *ptr; ptr++)
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