Make mbedTLS compile with MS-DOS DJGPP

Signed-off-by: SuperIlu <superilu@yahoo.com>
diff --git a/library/net_sockets.c b/library/net_sockets.c
index 87b5a43..730d13b 100644
--- a/library/net_sockets.c
+++ b/library/net_sockets.c
@@ -529,8 +529,8 @@
 #else
     struct timeval tv;
     tv.tv_sec  = usec / 1000000;
-#if defined(__unix__) || defined(__unix) || \
-    (defined(__APPLE__) && defined(__MACH__))
+#if (defined(__unix__) || defined(__unix) || \
+    (defined(__APPLE__) && defined(__MACH__))) && !defined(__DJGPP__)
     tv.tv_usec = (suseconds_t) usec % 1000000;
 #else
     tv.tv_usec = usec % 1000000;