[util] Add strlcpy helper

strncpy is not safe.

src/util/util_string.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstring>
 #include <string>
 #include <sstream>
 #include <vector>
@@ -39,5 +40,11 @@ namespace dxvk::str {
     format1(stream, args...);
     return stream.str();
   }
+
+  inline void strlcpy(char* dst, const char* src, size_t count) {
+    std::strncpy(dst, src, count);
+    if (count > 0)
+      dst[count - 1] = '\0';
+  }
   
 }