Fix CVE-2018-10963:

http://bugzilla.maptools.org/show_bug.cgi?id=2795
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-10963

Patch copied from upstream source repository:

https://gitlab.com/libtiff/libtiff/commit/de144fd228e4be8aa484c3caf3d814b6fa88c6d9

From de144fd228e4be8aa484c3caf3d814b6fa88c6d9 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Sat, 12 May 2018 14:24:15 +0200
Subject: [PATCH] TIFFWriteDirectorySec: avoid assertion. Fixes
 http://bugzilla.maptools.org/show_bug.cgi?id=2795. CVE-2018-10963

---
 libtiff/tif_dirwrite.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libtiff/tif_dirwrite.c b/libtiff/tif_dirwrite.c
index 2430de6d..c15a28db 100644
--- a/libtiff/tif_dirwrite.c
+++ b/libtiff/tif_dirwrite.c
@@ -695,8 +695,11 @@ TIFFWriteDirectorySec(TIFF* tif, int isimage, int imagedone, uint64* pdiroff)
 								}
 								break;
 							default:
-								assert(0);   /* we should never get here */
-								break;
+								TIFFErrorExt(tif->tif_clientdata,module,
+								            "Cannot write tag %d (%s)",
+								            TIFFFieldTag(o),
+                                                                            o->field_name ? o->field_name : "unknown");
+								goto bad;
 						}
 					}
 				}
-- 
2.17.0

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<tr><td><span title='2020-05-28 11:12:40 +0300'>2020-05-28</span></td><td><a href='/guix/commit/m4/guix.m4?id=03e6404936ef0974fdbc877d537b97b28e54124d'>doc: Remove explicit support for mips64el-linux.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2020-05-28 00:55:00 +0200'>2020-05-28</span></td><td><a href='/guix/commit/m4/guix.m4?id=c1dc50ab202fafedde3a6b70ce6339496ad53a51'>maint: Check whether Guile-Gcrypt is recent enough.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-02-22 00:45:58 +0100'>2020-02-22</span></td><td><a href='/guix/commit/m4/guix.m4?id=378918725259d221222dd0b1831fbaa3e0a17e1f'>build: Depend on guile-ssh 0.12.0</a><span class='msg-avail'>...</span></td><td>Lars-Dominik Braun</td></tr>
<tr><td><span title='2019-08-17 19:26:21 +0200'>2019-08-17</span></td><td><a href='/guix/commit/m4/guix.m4?id=611a64bd7e0893057cd04dcdc2a8d5e7ecc39e45'>build: 'GUIX_CHECK_GUILE_JSON' really checks for Guile-JSON 3.x.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-07-25 00:16:41 +0200'>2019-07-25</span></td><td><a href='/guix/commit/m4/guix.m4?id=81c3dc32244a17241d74eea9fa265edfcb326f6d'>maint: Switch to Guile-JSON 3.x.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-05-06 23:21:33 +0200'>2019-05-06</span></td><td><a href='/guix/commit/m4/guix.m4?id=fea338c6ca1922097fa233be85f424c152a4f507'>Add (guix lzlib).</a><span class='msg-avail'>...</span></td><td>Pierre Neidhardt</td></tr>