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))
 '/guix/'>summary</a><a href='/guix/refs/?id=65051fdce1ae3099d3626b70dd898216146723da'>refs</a><a class='active' href='/guix/log/gnu/packages/distributed.scm'>log</a><a href='/guix/tree/gnu/packages/distributed.scm?id=65051fdce1ae3099d3626b70dd898216146723da'>tree</a><a href='/guix/commit/gnu/packages/distributed.scm?id=65051fdce1ae3099d3626b70dd898216146723da'>commit</a><a href='/guix/diff/gnu/packages/distributed.scm?id=65051fdce1ae3099d3626b70dd898216146723da'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/distributed.scm'>
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<div class='path'>path: <a href='/guix/log/?id=65051fdce1ae3099d3626b70dd898216146723da'>root</a>/<a href='/guix/log/gnu?id=65051fdce1ae3099d3626b70dd898216146723da'>gnu</a>/<a href='/guix/log/gnu/packages?id=65051fdce1ae3099d3626b70dd898216146723da'>packages</a>/<a href='/guix/log/gnu/packages/distributed.scm?id=65051fdce1ae3099d3626b70dd898216146723da'>distributed.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/distributed.scm?id=65051fdce1ae3099d3626b70dd898216146723da&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-03-26 14:08:24 +0200'>2020-03-26</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=50e45d8629f5cd32f768324fd6a78c2e8da2a75e'>gnu: boinc-client: Update to 7.16.5.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client): Update to 7.16.5.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2020-03-26 14:08:24 +0200'>2020-03-26</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=f87d594238fb86dab8344a411fe62681ba0715b7'>gnu: boinc-server: Fix build.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-server)[inputs]: Replace openssl
with openssl-1.0, mariadb with mariadb:dev.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2020-02-16 22:46:38 +0100'>2020-02-16</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=3bc39f0c5dc3a6e5ad2feca7438e1f1d55e24771'>gnu: boinc-client: Trim synopsis.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client)[synopsis]: Remove package name.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-02-16 22:46:38 +0100'>2020-02-16</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=bcd3c48538cf7ab95b1c735880c866dccbdf7954'>gnu: boinc-client: Update to 7.16.4.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client): Update to 7.16.4.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-12-23 19:45:57 +0100'>2019-12-23</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=2f20666a74de54ec02147ff9473d44f98da7f80c'>gnu: boinc-client: Update to 7.16.3.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client): Update to 7.16.3.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-10-12 18:39:56 +0200'>2019-10-12</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=ecfc86a21dc257a2e495f69d9dc9d0fccb059d90'>gnu: BOINC: Add a source file name.</a><span class='msg-avail'>...<span class='msg-tooltip'>While at it, future-proof the URL as well.

* gnu/packages/distributed.scm (boinc-client)[source](file-name): New field.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-10-12 18:39:56 +0200'>2019-10-12</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=c21dae9b890d4bff598fe55134fde13a189a2c07'>gnu: BOINC: Update license.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client)[license]: Add LGPL3+.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-10-12 18:39:55 +0200'>2019-10-12</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=d72bfe075cc906d228e960c6bb515b7cd863dbd4'>gnu: BOINC: Remove redundant comment.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client)[description]: Don't mention
license terms.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-09-24 08:53:17 +0200'>2019-09-24</span></td><td><a href='/guix/commit/gnu/packages/distributed.scm?id=2d25b0c8bad3f0b9c5ccb91f5c4430d8245f4061'>gnu: Add boinc-client and boinc-server.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/distributed.scm (boinc-client, boinc-server): New variable.

Signed-off-by: Brian Leung &lt;leungbk@mailfence.com&gt;
</span></span></td><td>Brant Gardner</td></tr>