From Luigi Calori, Added CURL_IS_STATIC option to help hint to the libcurl's plugin build so that it can be select as static build

src/osgPlugins/curl/CMakeLists.txt

@@ -1,7 +1,14 @@
 #this file is automatically generated 
 
+OPTION(CURL_IS_STATIC "on if curl is a static lib " ON)
+MARK_AS_ADVANCED(CURL_IS_STATIC)
+
 IF(WIN32)
     SET(CMAKE_SHARED_LINKER_FLAGS_DEBUG "${CMAKE_SHARED_LINKER_FLAGS_DEBUG} /NODEFAULTLIB:MSVCRT")
+    IF(CURL_IS_STATIC)
+        ADD_DEFINITIONS(-DCURL_STATICLIB)
+        SET(TARGET_EXTERNAL_LIBRARIES ws2_32 winmm)
+    ENDIF(CURL_IS_STATIC)
 ENDIF(WIN32)
 
 INCLUDE_DIRECTORIES( ${CURL_INCLUDE_DIRS} )
@@ -10,5 +17,6 @@ SET(TARGET_SRC ReaderWriterCURL.cpp )
 
 SET(TARGET_LIBRARIES_VARS CURL_LIBRARY )
 
+
 #### end var setup  ###
 SETUP_PLUGIN(curl)