Small source code changes for Cygwin port of OSG.

src/osg/GLExtensions.cpp

@@ -60,7 +60,7 @@ const bool osg::isGLExtensionSupported(const char *extension)
 
 void* osg::getGLExtensionFuncPtr(const char *funcName)
 {
-#if defined(_WIN32)
+#if defined(_WIN32) || defined(__CYGWIN__)
    return wglGetProcAddress(funcName);
 #elif defined(macintosh)
    return NULL;

src/osgDB/Registry.cpp

@@ -221,7 +221,7 @@ std::string Registry::createLibraryNameForExt(const std::string& ext)
     ExtensionAliasMap::iterator itr=_extAliasMap.find(ext);
     if (itr!=_extAliasMap.end()) return createLibraryNameForExt(itr->second);
 
-#ifdef WIN32
+#if defined(WIN32)
 #   ifdef _DEBUG
     return "osgdb_"+ext+"d.dll";
 #   else