package/cegui: add missing <string.h> include

Backport an upstream patch to fix a missing <string.h> include.

Fixes:

  http://autobuild.buildroot.net/results/7507b3c5cdcae04804a750f688057adae93cd329/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/cegui/0001-XMLParser.cpp-include-string.h.patch

@@ -0,0 +1,37 @@
+From b98ed87225fa3c0f156b0798ca5c285d8fa8fac1 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Tue, 15 Jun 2021 07:27:41 +0200
+Subject: [PATCH] XMLParser.cpp: include string.h
+
+Include string.h to avoid the following build failure:
+
+/home/buildroot/autobuild/run/instance-3/output-1/build/cegui-00b4e1fe174da53b7ed726ab5970ba51bd5b5ee0/cegui/src/XMLParserModules/RapidXML/XMLParser.cpp:73:5: error: 'memcpy' was not declared in this scope
+   73 |     memcpy(buf, source.getDataPtr(), size);
+      |     ^~~~~~
+
+Fixes:
+ - http://autobuild.buildroot.org/results/1cb09e5f52435efc505c61707b2d5d2ee871524b
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Upstream: 628f7edf4b420f752f1965ea11e5e747e3ff93b0
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ cegui/src/XMLParserModules/RapidXML/XMLParser.cpp | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/cegui/src/XMLParserModules/RapidXML/XMLParser.cpp b/cegui/src/XMLParserModules/RapidXML/XMLParser.cpp
+index 810ea6bbf..59822fc80 100644
+--- a/cegui/src/XMLParserModules/RapidXML/XMLParser.cpp
++++ b/cegui/src/XMLParserModules/RapidXML/XMLParser.cpp
+@@ -38,6 +38,8 @@
+ #include "CEGUI/Logger.h"
+ #include "CEGUI/Exceptions.h"
+ 
++#include <string.h>
++
+ // Start of CEGUI namespace section
+ namespace CEGUI
+ {
+-- 
+2.31.1
+