Bug 1777968 - Fix the header name, r=necko-reviewers,dragana

On mingw32 platform, the header name should be lower case

Differential Revision: https://phabricator.services.mozilla.com/D151110

netwerk/base/nsServerSocket.cpp

@@ -19,7 +19,7 @@
 #include "nsIFile.h"
 #if defined(XP_WIN)
 #  include "private/pprio.h"
-#  include <Winsock2.h>
+#  include <winsock2.h>
 #  include <mstcpip.h>
 
 #  ifndef IPV6_V6ONLY