Updates to the flush rendering objects function calls to allow for

managment of amount of time available to do gl delete's.  This control is
required for constant frame rate applications.

src/osg/VertexProgram.cpp

@@ -34,7 +34,7 @@ void VertexProgram::deleteVertexProgramObject(unsigned int contextID,GLuint hand
 }
 
 
-void VertexProgram::flushDeletedVertexProgramObjects(unsigned int contextID)
+void VertexProgram::flushDeletedVertexProgramObjects(unsigned int contextID,double currentTime, double& availableTime)
 {
     const Extensions* extensions = getExtensions(contextID,true);