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 b/localedata/Makefile
index 65079f9eb8..14818f84e0 100644
--- a/localedata/Makefile
+++ b/localedata/Makefile
@@ -169,7 +169,8 @@ endif
 # Files to install.
 install-others := $(addprefix $(inst_i18ndir)/, \
 			      $(addsuffix .gz, $(charmaps)) \
-			      $(locales))
+			      $(locales)) \
+                   $(inst_i18ndir)/SUPPORTED
 
 tests: $(objdir)/iconvdata/gconv-modules
 
@@ -380,6 +381,14 @@ 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 $@
+
 INSTALL-SUPPORTED-LOCALE-ARCHIVE=$(addprefix install-archive-, $(SUPPORTED-LOCALES))
 INSTALL-SUPPORTED-LOCALE-FILES=$(addprefix install-files-, $(SUPPORTED-LOCALES))
 </a><a href='/guix/refs/?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>refs</a><a class='active' href='/guix/log/gnu/services/ssh.scm'>log</a><a href='/guix/tree/gnu/services/ssh.scm?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>tree</a><a href='/guix/commit/gnu/services/ssh.scm?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>commit</a><a href='/guix/diff/gnu/services/ssh.scm?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/services/ssh.scm'>
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<div class='path'>path: <a href='/guix/log/?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>root</a>/<a href='/guix/log/gnu?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>gnu</a>/<a href='/guix/log/gnu/services?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>services</a>/<a href='/guix/log/gnu/services/ssh.scm?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741'>ssh.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/services/ssh.scm?id=4796b5d6d18dcc0f1b6c8e134977ebdb575c5741&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-10-01 10:15:29 +0300'>2020-10-01</span></td><td><a href='/guix/commit/gnu/services/ssh.scm?id=da6aec32cf13cf06cfda909c45f7f35625c4e3fa'>gnu: Add webssh service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/ssh.scm:
(&lt;webssh-configuration&gt;): New record type.
(%webssh-configuration-nginx, webssh-service-type): New variables.
(webssh-account, webssh-activation, webssh-shepherd-service): New procedures.
* doc/guix.texi: Document this.
</span></span></td><td>Oleg Pykhalov</td></tr>
<tr><td><span title='2020-05-05 15:32:40 +0300'>2020-05-05</span></td><td><a href='/guix/commit/gnu/services/ssh.scm?id=051f3254cd56aa8f3cb65a7e35ef8578af2cd3c5'>gnu: Add AutoSSH service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/ssh.scm (&lt;autossh-configuration&gt;): New record type.
(autossh-service-type): New variable.
(autossh-service-activation, autossh-file-name): New procedures.
* doc/guix.texi (Networking Services): Document this.

Signed-off-by: Oleg Pykhalov &lt;go.wigust@gmail.com&gt;
</span></span></td><td>pinoaffe</td></tr>
<tr><td><span title='2019-12-04 08:31:39 -0500'>2019-12-04</span></td><td><a href='/guix/commit/gnu/services/ssh.scm?id=1a7633c2397714c492482282da670e47f7dc8177'>services: SSH services: Provide 'ssh' and 'sshd' Shepherd services.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/ssh.scm (lsh-shepherd-service, dropbear-shepherd-service,
openssh-sheperd-service): Add 'ssh' and 'sshd' to provision.
</span></span></td><td>Leo Famulari</td></tr>