package/localedef: build issue with old glibc (<= 2.38)

While building host-localedef from glibc 2.38 sources, it uses the
features.h header from its sources that define _ISOC2X_SOURCE 1 as
soon as _GNU_SOURCE is defined.

_ISOC2X_SOURCE enable __GLIBC_USE_ISOC2X 1 that enable the header
redirection to use __isoc23_* functions introduced in glibc 2.38 [1].

If an older version is installed on the host, those functions
doesn't exist and break the build.

Add a local patch to keep _ISOC2X_SOURCE and __GLIBC_USE_ISOC2X
disabled.

Fixes:
host-localedef-2.38-13-g92201f16cbcfd9eafe314ef6654be2ea7ba25675/build/locale/ld-ctype.o: in function `ctype_read':
ld-ctype.c:(.text+0x6cef): undefined reference to `__isoc23_strtoul'

(glibc 2.31 installed on the host)

[1] https://sourceware.org/git/?p=glibc.git;a=commit;h=64924422a99690d147a166b4de3103f3bf3eaf6c

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/localedef/0003-HACK-keep-_ISOC2X_SOURCE-undefined-to-build-localede.patch

@@ -0,0 +1,32 @@
+From babfa64585bef6c53c1d399a1c244aea89437c9e Mon Sep 17 00:00:00 2001
+From: Romain Naour <romain.naour@gmail.com>
+Date: Sat, 9 Sep 2023 23:58:50 +0200
+Subject: [PATCH] HACK: keep _ISOC2X_SOURCE undefined to build localedef with
+ old glibc
+
+Fixes:
+host-localedef-2.38-13-g92201f16cbcfd9eafe314ef6654be2ea7ba25675/build/locale/ld-ctype.o: in function `ctype_read':
+ld-ctype.c:(.text+0x6cef): undefined reference to `__isoc23_strtoul'
+
+Upstream: Not applicable
+
+Signed-off-by: Romain Naour <romain.naour@gmail.com>
+---
+ include/features.h | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/include/features.h b/include/features.h
+index 7c51b4a2e4..f385370d18 100644
+--- a/include/features.h
++++ b/include/features.h
+@@ -207,7 +207,6 @@
+ # undef  _ISOC11_SOURCE
+ # define _ISOC11_SOURCE	1
+ # undef  _ISOC2X_SOURCE
+-# define _ISOC2X_SOURCE	1
+ # undef  _POSIX_SOURCE
+ # define _POSIX_SOURCE	1
+ # undef  _POSIX_C_SOURCE
+-- 
+2.41.0
+