This patch removes the _XOPEN_SOURCE preprocessor directive as it does not seem to be needed.
Setting it removes the definition of strdup, which is used in filter-datatypes.c.

Patch by Roel Janssen <roel@gnu.org>
*** a/src/frontend/filter-datatypes.c	1970-01-01 01:00:00.000000000 +0100
--- b/src/frontend/filter-datatypes.c	2018-04-03 17:39:23.177905592 +0200
***************
*** 18,24 ****
   *  Copyright (C) 2006 Steve Harris for Garlik
   */
  
- #define _XOPEN_SOURCE
  #include <stdlib.h>
  #include <string.h>
  #include <math.h>
--- 18,23 ----
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<tr><td><span title='2022-09-01 23:37:13 +0200'>2022-09-01</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=08380429b8d849a40489b48110234d3a2257fa2d'>gnu: boost: Update to 1.80.0.</a><span class='msg-avail'>...</span></td><td>Greg Hogan</td></tr>
<tr><td><span title='2022-08-11 23:36:10 +0200'>2022-08-11</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=77eb3008e350c069e0ae8df6a91bf0ebdcfc2ac0'>Merge branch 'staging' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-08-11 00:21:11 +0200'>2022-08-11</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=b424ca573df717acc7d5a074b69218eaaeb19ce3'>gnu: mdds: Update to 2.0.3.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-07-06 00:35:17 +0200'>2022-07-06</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=eb32bcea32c419f7b501fe292535d4b65d6031d6'>gnu: Boost: Use #:configure-flags.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-07-06 00:35:17 +0200'>2022-07-06</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=f12ca428b866c25a3cd9740d9e471e06b8bcaef3'>gnu: Boost: Avoid usage of 'this-package-input'.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
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<tr><td><span title='2022-07-06 00:35:17 +0200'>2022-07-06</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=526071290f7329250adfdd6fa17de00ac84b1773'>gnu: boost, boost-static: Consolidate libboost_python phases.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-07-06 00:35:17 +0200'>2022-07-06</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=d1e9f626b4d6230fa41db920cf87af9281ffe5de'>gnu: boost-mpi: Remove input labels.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-06-30 23:26:19 +0200'>2022-06-30</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=5e2ecfab7cdbb0cef07708a83a4d8994bc323a36'>gnu: Boost: Use G-expressions.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2022-06-08 14:46:24 +0200'>2022-06-08</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=8c3e9da13a3c92a7db308db8c0d81cb474ad7799'>Merge branch 'master' into core-updates</a></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-05-31 14:54:06 -0400'>2022-05-31</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=098372a81e61f92bab4439c9bbaf43a73e1649b3'>gnu: Remove boost-with-python2.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-05-08 11:25:26 +0200'>2022-05-08</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=b8f4ed8f5dee0b268415dd13a3d6d37d36652701'>gnu: boost: Update to 1.79.0.</a><span class='msg-avail'>...</span></td><td>Greg Hogan</td></tr>
<tr><td><span title='2022-03-28 09:23:41 +0200'>2022-03-28</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=a59afdc92e8d29edf2cb2193f967715e46c885c7'>gnu: boost: Update to 1.78.0.</a><span class='msg-avail'>...</span></td><td>Greg Hogan</td></tr>