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))
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<tr><td><span title='2021-02-09 15:06:08 -0500'>2021-02-09</span></td><td><a href='/guix/commit/gnu/packages/xiph.scm?id=d00380b0077b0df2a0b790bb115d07c1533b8863'>gnu: vorbis-tools: Update to 1.4.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/xiph.scm (vorbis-tools): Update to 1.4.2.
(source): Remove obsolete patches.
* gnu/packages/patches/vorbis-tools-CVE-2014-9638+CVE-2014-9639.patch,
gnu/packages/patches/vorbis-tools-CVE-2014-9640.patch,
gnu/packages/patches/vorbis-tools-CVE-2015-6749.patch: Delete files.
* gnu/local.mk (dist_patch_DATA): Remove them.

Signed-off-by: Leo Famulari &lt;leo@famulari.name&gt;
</span></span></td><td>Vincent Legoll</td></tr>
<tr><td><span title='2021-01-03 06:55:31 +0100'>2021-01-03</span></td><td><a href='/guix/commit/gnu/packages/xiph.scm?id=15bffa0cc2470ffc48d40fbc6320b5d5d786373c'>gnu: libshout: Update to 2.4.5.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/xiph.scm (libshout): Update to 2.4.5.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-10-13 23:39:27 +0200'>2020-10-13</span></td><td><a href='/guix/commit/gnu/packages/xiph.scm?id=f7175626ffce578be1bc6df4916a129f86557872'>Merge branch 'master' into staging</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2020-10-06 01:04:47 +0200'>2020-10-06</span></td><td><a href='/guix/commit/gnu/packages/xiph.scm?id=d3b9cbd9c8728f977aa12708d0b034e609f07436'>gnu: libshout: Update to 2.4.4.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/xiph.scm (libshout): Update to 2.4.4.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>