This patch solves the issue raised by CVE-2014-9116.

We correctly redefine what are the whitespace characters as per RFC5322; by
doing so we prevent mutt_substrdup from being used in a way that could lead to
a segfault.

The lib.c part was written by Antonio Radici <antonio@debian.org> to prevent
crashes due to this kind of bugs from happening again.

--- lib.c.orig
+++ lib.c
@@ -815,6 +815,9 @@ char *mutt_substrdup (const char *begin,
   size_t len;
   char *p;
 
+  if (end != NULL && end < begin)
+    return NULL;
+
   if (end)
     len = end - begin;
   else
--- lib.h.orig
+++ lib.h
@@ -98,7 +98,7 @@
    on some systems */
 # define SKIPWS(c) while (*(c) && isspace ((unsigned char) *(c))) c++;
 
-#define EMAIL_WSP " \t\r\n"
+#define EMAIL_WSP " \t\r"
 
 /* skip over WSP as defined by RFC5322.  This is used primarily for parsing
  * header fields. */