tslib: fix gcc-14 build

temporary fix until tslib can be updated

fixes missing header

src/ts_reconfig.c: In function 'ts_reconfig':
src/ts_reconfig.c:43:9: error: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
   43 |         memset(ts, 0, sizeof(struct tsdev));
      |         ^~~~~~
src/ts_reconfig.c:21:1: note: include '<string.h>' or provide a declaration of 'memset'
   20 | #include "tslib-private.h"
  +++ |+#include <string.h>
   21 |
src/ts_reconfig.c:43:9: warning:incompatible implicit declaration of built-in function 'memset' [-Wbuiltin-declaration-mismatch]
   43 |         memset(ts, 0, sizeof(struct tsdev));
      |         ^~~~~~
src/ts_reconfig.c:43:9: note: include '<string.h>' or provide a declaration of 'memset'

packages/addons/addon-depends/tslib/patches/tslib-40-fix-gcc-14-1.patch

@@ -0,0 +1,10 @@
+--- a/src/ts_reconfig.c	2024-05-23 07:01:59.264165839 +0000
++++ b/src/ts_reconfig.c	2024-05-23 07:01:54.034129359 +0000
+@@ -16,6 +16,7 @@
+ #include <unistd.h>
+ #endif
+ #include <dlfcn.h>
++#include <string.h>
+ 
+ #include "tslib-private.h"
+