lyx: fix build with gcc>=12

srcpkgs/lyx/patches/lyx-2.3.6.1-gcc12.patch

@@ -0,0 +1,22 @@
+https://src.fedoraproject.org/rpms/lyx/raw/rawhide/f/lyx-2.3.6-fix-gcc12.patch
+https://bugs.gentoo.org/841743
+--- a/src/insets/InsetListings.cpp
++++ b/src/insets/InsetListings.cpp
+@@ -44,6 +44,7 @@
+ 
+ #include "support/regex.h"
+ 
++#include <cstring>
+ #include <sstream>
+ 
+ using namespace std;
+--- a/src/lyxfind.cpp
++++ b/src/lyxfind.cpp
+@@ -52,6 +52,7 @@
+ #include "support/lstrings.h"
+ 
+ #include "support/regex.h"
++#include <iterator>
+ 
+ using namespace std;
+ using namespace lyx::support;