Cross platform build fixes.

src/osgFX/MultiTextureControl.cpp

@@ -16,6 +16,7 @@
 
 #include <osgFX/MultiTextureControl>
 
+using namespace osg;
 using namespace osgFX;
 
 MultiTextureControl::MultiTextureControl()

src/osgSim/ImpostorSprite.cpp

@@ -26,6 +26,7 @@
 
 #include <osgSim/ImpostorSprite>
 
+using namespace osg;
 using namespace osgSim;
 
 ImpostorSprite::ImpostorSprite()
@@ -45,6 +46,9 @@ ImpostorSprite::ImpostorSprite()
     _color.set(1.0f, 1.0f, 1.0f, 1.0f );
 }
 
+ImpostorSprite::ImpostorSprite(const ImpostorSprite&): Drawable() {}
+
+
 ImpostorSprite::~ImpostorSprite()
 {
     if (_ism)

src/osgText/Text.cpp

@@ -23,11 +23,11 @@
 
 #include "DefaultFont.h"
 
+using namespace osg;
 using namespace osgText;
 
 //#define TREES_CODE_FOR_MAKING_SPACES_EDITABLE
 
-
 Text::Text():
     _fontWidth(32),
     _fontHeight(32),