a stub for winsock2

dtool/src/parser-inc/Sources.pp

@@ -1,7 +1,7 @@
 #define INSTALL_PARSER_INC \
     algorithm deque ft2build.h hash_map hash_set iostream list map memory \
     pair pthread.h queue set stack stdcompare.h stdtypedefs.h \
-    string vector windows.h zlib.h files.h hex.h \
+    string vector windows.h winsock2.h zlib.h files.h hex.h \
     md5.h evp.h bits/pthreadtypes.h \
     openssl/md5.h openssl/evp.h openssl/rand.h openssl/ssl.h openssl/x509.h openssl/err.h \
     nurbs.hh stddef.h krb5.h MainHelix.h dllpath.h hxcom.h \