Updates for Cygwin port, from Norman Vine.

src/osgPlugins/zip/ReaderWriterZIP.cpp

@@ -13,7 +13,7 @@
 #include <osgDB/FileNameUtils>
 #include <osgDB/Registry>
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(__CYGWIN__)
 #include <direct.h>
 #else
 #include <unistd.h>
@@ -40,7 +40,7 @@ class ReaderWriterZIP : public osgDB::ReaderWriter
             char dirname[128];
             char command[1024];
 
-        #ifdef _WIN32
+		#if defined(_WIN32) && !defined(__CYGWIN__)
             strcpy(dirname, "C:/Windows/Temp/.osgdb_zip");
             mkdir(dirname);
             sprintf( command,
@@ -83,7 +83,7 @@ class ReaderWriterZIP : public osgDB::ReaderWriter
 
             osgDB::Registry::instance()->setCreateNodeFromImage(prevCreateNodeFromImage);
 
-        #ifdef _WIN32
+		#if defined(_WIN32) && !defined(__CYGWIN__)
             // note, is this the right command for windows?
             // is there any way of overiding the Y/N option? RO.
             sprintf( command, "erase %s", dirname );