libubootenv: backport patch to fix unknown type name 'size_t'

Fix:
../recipe-sysroot/usr/include/libuboot.h:29:2: error: unknown type name 'size_t'
size_t          envsize;
^

This error can be avoided by using CXXFLAGS:append = " -include cstddef"
but this way would be needed in all recipes that use libuboot.h.
Therefore, Backport the patch to include <cstddef> in C++ builds.

(From OE-Core rev: e401a16d8e26d25cec95fcea98d6530036cffca1)

Signed-off-by: Youngseok Jeong <youngseok1.jeong@lge.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-bsp/u-boot/files/0001-Include-cstddef-in-the-header-for-C.patch

@@ -0,0 +1,27 @@
+From 10c9a571f1c0472799f72b1924b039aab231e95f Mon Sep 17 00:00:00 2001
+From: Oleksandr Kravchuk <open.source@oleksandr-kravchuk.com>
+Date: Thu, 16 Dec 2021 16:19:50 +0100
+Subject: [PATCH] Include cstddef in the header for C++
+
+So C++ compiler always has access to the definition of size_t.
+
+Signed-off-by: Oleksandr Kravchuk <open.source@oleksandr-kravchuk.com>
+Signed-off-by: Youngseok Jeong <youngseok1.jeong@lge.com>
+Upstream-Status: Backport [v0.3.3 https://github.com/sbabic/libubootenv/pull/19/commits/764226a7de2ea79b182d92829922489537c766fa]
+---
+ src/libuboot.h | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/src/libuboot.h b/src/libuboot.h
+index 88f0558..1f305f4 100644
+--- a/src/libuboot.h
++++ b/src/libuboot.h
+@@ -6,6 +6,8 @@
+  */
+ 
+ #ifdef __cplusplus
++#include <cstddef>
++
+ extern "C" {
+ #endif
+ 

meta/recipes-bsp/u-boot/libubootenv_0.3.2.bb

@@ -10,7 +10,11 @@ LICENSE = "LGPL-2.1-only"
 LIC_FILES_CHKSUM = "file://Licenses/lgpl-2.1.txt;md5=4fbd65380cdd255951079008b364516c"
 SECTION = "libs"
 
-SRC_URI = "git://github.com/sbabic/libubootenv;protocol=https;branch=master"
+SRC_URI = " \
+    git://github.com/sbabic/libubootenv;protocol=https;branch=master \
+    file://0001-Include-cstddef-in-the-header-for-C.patch \
+"
+
 SRCREV = "ba7564f5006d09bec51058cf4f5ac90d4dc18b3c"
 
 S = "${WORKDIR}/git"