This patch is taken from debian's glibc package (generate-supported.mk).
It install the localedata/SUPPORTED file of the glibc. This file lists
all the supported locales of the glibc.

diff --git a/localedata/Makefile.old b/localedata/Makefile
index 34877c0..a61d9b9 100644
--- a/localedata/Makefile.old
+++ b/localedata/Makefile
@@ -91,7 +91,8 @@ endif
 # Files to install.
 install-others := $(addprefix $(inst_i18ndir)/, \
 			      $(addsuffix .gz, $(charmaps)) \
-			      $(locales))
+			      $(locales)) \
+                   $(inst_i18ndir)/SUPPORTED
 
 tests: $(objdir)/iconvdata/gconv-modules
 
@@ -195,6 +196,14 @@ endif
 
 include SUPPORTED
 
+$(inst_i18ndir)/SUPPORTED: SUPPORTED $(+force)
+	for locale in $(SUPPORTED-LOCALES); do \
+		[ $$locale = true ] && continue; \
+		echo $$locale | sed 's,/, ,' >> LOCALES; \
+	done
+	$(make-target-directory)
+	$(INSTALL_DATA) LOCALES $@
+
 INSTALL-SUPPORTED-LOCALES=$(addprefix install-, $(SUPPORTED-LOCALES))
 
 # Sometimes the whole collection of locale files should be installed.
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<div class='path'>path: <a href='/guix/log/?id=5269899aacd897aedc3defb2022e4655281c3779'>root</a>/<a href='/guix/log/doc?id=5269899aacd897aedc3defb2022e4655281c3779'>doc</a>/<a href='/guix/log/doc/htmlxref.cnf?id=5269899aacd897aedc3defb2022e4655281c3779'>htmlxref.cnf</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/doc/htmlxref.cnf?id=5269899aacd897aedc3defb2022e4655281c3779&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-01-12 00:19:10 +0100'>2020-01-12</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=30d83f445b70ebce7f01eaa91c8f418ff0a98321'>doc: Update htmlxref.cnf.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/htmlxref.cnf: Update from Texinfo.  Add entries for "mes",
"guix.ru", and "guix.zh_CN".
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-05-04 23:07:38 +0200'>2019-05-04</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=e8f8363cdebb24dc359cadba7ae0a689fb21fb99'>doc: Update htmlxref.cnf.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/htmlxref.cnf (G): Switch to https.
(geiser, guix.de, guix.es, hurd): New entries.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-07-05 22:16:10 +0200'>2018-07-05</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=c35f77c5a07690fc9d369ed4b751a5a9e5de6cf1'>doc: Update URL of the Emacs-Guix manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/htmlxref.cnf (EMACS_GUIX): Update URL.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-07-05 22:13:23 +0200'>2018-07-05</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=56b4dabc2ba3446ff212e0d4d9e2df15fc25e88f'>doc: Mention translations of the manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Top): Add note about l10n.
* doc/htmlxref.cnf: Add "guix.fr".
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-05-30 18:30:39 +0300'>2017-05-30</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=f753c2829913a9bb61dc266f4b1db8275e34a461'>doc: htmlxref: Fix link to Emacs-Guix manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>Reported-by: Ludovic Courtès &lt;ludo@gnu.org&gt;

This fixes a regression introduced by commit
8ca0c88a894c685b624757e38ee7663534f03460.

* doc/htmlxref.cnf (EMACS_GUIX): Fix the link to 'html_node'.
</span></span></td><td>Alex Kost</td></tr>
<tr><td><span title='2017-05-04 22:45:53 +0300'>2017-05-04</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=8ca0c88a894c685b624757e38ee7663534f03460'>doc: Add references to Emacs-Guix manual.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/htmlxref.cnf: Add links to the real manual.
* doc/contributing.texi (Formatting Code): Add reference to it.
* doc/guix.texi (Package Management): Likewise.
</span></span></td><td>Alex Kost</td></tr>
<tr><td><span title='2016-12-29 23:40:24 +0300'>2016-12-29</span></td><td><a href='/guix/commit/doc/htmlxref.cnf?id=deb6276dda81a69da38e842d269c5370a28fa5cf'>Remove Emacs interface.</a><span class='msg-avail'>...<span class='msg-tooltip'>* emacs/guix-about.el: Remove file.
* emacs/guix-backend.el: Likewise.
* emacs/guix-base.el: Likewise.
* emacs/guix-buffer.el: Likewise.
* emacs/guix-build-log.el: Likewise.
* emacs/guix-command.el: Likewise.
* emacs/guix-config.el.in: Likewise.
* emacs/guix-devel.el: Likewise.
* emacs/guix-entry.el: Likewise.
* emacs/guix-external.el: Likewise.
* emacs/guix-geiser.el: Likewise.
* emacs/guix-guile.el: Likewise.
* emacs/guix-help-vars.el: Likewise.
* emacs/guix-helper.scm.in: Likewise.
* emacs/guix-history.el: Likewise.
* emacs/guix-hydra-build.el: Likewise.
* emacs/guix-hydra-jobset.el: Likewise.
* emacs/guix-hydra.el: Likewise.
* emacs/guix-info.el: Likewise.
* emacs/guix-init.el: Likewise.
* emacs/guix-license.el: Likewise.
* emacs/guix-list.el: Likewise.
* emacs/guix-location.el: Likewise.
* emacs/guix-main.scm: Likewise.
* emacs/guix-messages.el: Likewise.
* emacs/guix-pcomplete.el: Likewise.
* emacs/guix-popup.el: Likewise.
* emacs/guix-prettify.el: Likewise.
* emacs/guix-profiles.el: Likewise.
* emacs/guix-read.el: Likewise.
* emacs/guix-ui-generation.el: Likewise.
* emacs/guix-ui-license.el: Likewise.
* emacs/guix-ui-location.el: Likewise.
* emacs/guix-ui-package.el: Likewise.
* emacs/guix-ui-system-generation.el: Likewise.
* emacs/guix-ui.el: Likewise.
* emacs/guix-utils.el: Likewise.
* emacs/local.mk: Likewise.
* doc/emacs.texi: Likewise.
* doc/guix.texi: Remove cross-references to Emacs nodes.
(Package Management): Mention 'emacs-guix' package.
* doc/contributing.texi (The Perfect Setup): Remove the reference.
* doc/htmlxref.cnf: Add 'emacs-guix' URL.
* Makefile.am: Remove Emacs stuff.
* configure.ac: Likewise.
* gnu/packages/package-management.scm (guix-0.12.0)[native-inputs]:
Remove "emacs".
[propagated-inputs]: Remove "geiser" and "emacs-magit-popup".

Co-authored-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Alex Kost</td></tr>