Fix cross-build linux->mingw (#320)

diff --git a/usrsctplib/netinet/sctp_os_userspace.h b/usrsctplib/netinet/sctp_os_userspace.h
index a97b515..765deed 100755
--- a/usrsctplib/netinet/sctp_os_userspace.h
+++ b/usrsctplib/netinet/sctp_os_userspace.h
@@ -47,8 +47,8 @@
 #include <winsock2.h>
 #include <ws2tcpip.h>
 #include <iphlpapi.h>
-#include <Mswsock.h>
-#include <Windows.h>
+#include <mswsock.h>
+#include <windows.h>
 #include "user_environment.h"
 typedef CRITICAL_SECTION userland_mutex_t;
 #if WINVER < 0x0600