Fix error found with "-Werror=format-security" flag

Patch borrowed from Fedora

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

Upstream-Status: Pending

diff -Naur imap-2007f.orig/src/osdep/unix/flocklnx.c imap-2007f/src/osdep/unix/flocklnx.c
--- imap-2007f.orig/src/osdep/unix/flocklnx.c	2011-07-23 02:20:11.000000000 +0200
+++ imap-2007f/src/osdep/unix/flocklnx.c	2014-04-14 19:17:46.429000000 +0200
@@ -57,7 +57,7 @@
     case ENOLCK:		/* lock table is full */
       sprintf (tmp,"File locking failure: %s",strerror (errno));
       mm_log (tmp,WARN);	/* give the user a warning of what happened */
-      if (!logged++) syslog (LOG_ERR,tmp);
+      if (!logged++) syslog (LOG_ERR, "%s", tmp);
 				/* return failure if non-blocking lock */
       if (op & LOCK_NB) return -1;
       sleep (5);		/* slow down in case it loops */