A couple of patches to build on Arch

[Timh1970]

I have just packaged your app for Arch and there are a couple of very minor issues that I have had to patch

Patch 1

--- a/src/visp/arch/swin.cpp
+++ b/src/visp/arch/swin.cpp
@@ -1,5 +1,7 @@
 #include "visp/arch/swin.h"
 #include "util/string.h"
 #include "visp/nn.h"
+#include <cmath>
+#include <cstring>
 
 namespace visp {
 namespace swin {

Patch 2

--- a/src/visp/ml.cpp
+++ b/src/visp/ml.cpp
@@ -4,6 +4,7 @@
 #include <algorithm>
 #include <array>
+#include <cstring>
 #include <thread>
 #include <vector>