Fix MSVC warnings in library and programs
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index 76e3b31..f6e0cd0 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -491,7 +491,7 @@
      */
     if( opt.seed == 0 )
     {
-        opt.seed = time( NULL );
+        opt.seed = (unsigned int) time( NULL );
         mbedtls_printf( "  . Pseudo-random seed: %u\n", opt.seed );
     }