This patch is borrowed from Debian's patches for plink

Author: Peter Green <plugwash@p10link.net>
Puropose: Fallback to endian.h if all else fails on 64bit machines
Closes: #528659
Forwarded: Shaun Purcell <plink@chgr.mgh.harvard.edu>
License: same as plink itself.
===================================================================
--- plink-1.06.orig/Rsrv.h	2009-05-15 03:35:29.000000000 +0100
+++ plink-1.06/Rsrv.h	2009-05-15 03:35:41.000000000 +0100
@@ -313,7 +313,18 @@
 #define __BIG_ENDIAN__ 1
 #define SWAPEND 1
 #elif ! defined Win32 /* Windows is little-endian is most cases, anywhere else we're stuck */
-#error "Cannot determine endianness. Make sure config.h is included or __{BIG|LITTLE}_ENDIAN__ is defined ."
+  //try endian.h before we finally bail out
+  #include <endian.h>
+  #if __BYTE_ORDER == __LITTLE_ENDIAN
+    #warning using little endian based on information from endian.h
+    #define __LITTLE_ENDIAN__ 1
+  #elif __BYTE_ORDER == __BIG_ENDIAN
+    #warning using big endian based on information from endian.h
+    #define __BIG_ENDIAN__ 1
+    #define SWAPEND 1
+  #else    
+    #error "Cannot determine endianness. Make sure config.h is included or __{BIG|LITTLE}_ENDIAN__ is defined ."
+  #endif    
 #endif
 
 /* FIXME: all the mess below needs more efficient implementation - the current one is so messy to work around alignment problems on some platforms like Sun and HP 9000 */
fc'>commit</a><a href='/guix/diff/gnu/packages/abiword.scm?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/abiword.scm'>
<input type='hidden' name='id' value='8a5924dcfecf02ae755d717cd11643b8a42bd7fc'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc'>root</a>/<a href='/guix/log/gnu?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc'>gnu</a>/<a href='/guix/log/gnu/packages?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc'>packages</a>/<a href='/guix/log/gnu/packages/abiword.scm?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc'>abiword.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/abiword.scm?id=8a5924dcfecf02ae755d717cd11643b8a42bd7fc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-10-20 14:00:12 +0200'>2019-10-20</span></td><td><a href='/guix/commit/gnu/packages/abiword.scm?id=0fe041bd9fa87d23b44969a3bcd99b1165a0f06e'>gnu: Remove more GCC &lt; 7 workarounds.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/abiword.scm (abiword)[arguments]: Do not pass "-std=c++11" to
the GCC command line.
* gnu/packages/aidc.scm (zbar)[arguments]: Likewise.
* gnu/packages/android.scm (android-libbase, android-libcutils,
android-libziparchive, fastboot)[arguments]: Likewise.
* gnu/packages/audio.scm (azr3, guitarix, suil)[arguments]: Likewise.
* gnu/packages/bioinformatics.scm (bless)[arguments]: Likewise.
* gnu/packages/bittorrent.scm (libtorrent-rasterbar)[arguments]: Likewise.
* gnu/packages/code.scm (rtags)[arguments]: Likewise.
* gnu/packages/coq.scm (coq-gappa)[arguments]: Likewise.
* gnu/packages/emulators.scm (dolphin-emu)[arguments]: Likewise.
* gnu/packages/engineering.scm (xyce-serial, xyce-parallel)[arguments]: Likewise.
* gnu/packages/gnupg.scm (pinentry-qt)[arguments]: Likewise.
* gnu/packages/gobby.scm (libnet6, obby)[arguments]: Likewise.
* gnu/packages/graph.scm (python-faiss)[arguments]: Likewise.
* gnu/packages/graphics.scm (povray)[arguments]: Likewise.
* gnu/packages/image-processing.scm (opencv, itk-snap)[arguments]: Likewise.
* gnu/packages/image.scm (freeimage)[arguments]: Likewise.
* gnu/packages/kodi.scm (crossguid)[arguments]: Likewise.
* gnu/packages/music.scm (amsynth, qmidiarp, qmidiroute, seq24)[arguments]: Likewise.
* gnu/packages/pdf.scm (python-poppler-qt5)[arguments]: Likewise.
* gnu/packages/sagemath.scm (lcalc)[arguments]: Likewise.
* gnu/packages/video.scm (vlc, mlt, v4l-utils)[arguments]: Likewise.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-02-08 23:51:13 +0100'>2019-02-08</span></td><td><a href='/guix/commit/gnu/packages/abiword.scm?id=7428d1693a281ee06e918310d95543da5349153e'>gnu: abiword: Don't use NAME in source URI.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/abiword.scm (abiword)[source]: Hard-code name.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2018-10-09 09:56:35 +0300'>2018-10-09</span></td><td><a href='/guix/commit/gnu/packages/abiword.scm?id=07b0662754014f7ac8ab81ce6a8878d0cc206b19'>gnu: abiword: Remove wmf support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/abiword.scm (abiword)[arguments]: Remove 'wmf' from the
list of enabled plugins.
</span></span></td><td>Efraim Flashner</td></tr>