Proper headless build fix

simgear/misc/parse_color.cxx

@@ -16,6 +16,10 @@
 // License along with this library; if not, write to the Free Software
 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
 
+#include <simgear_config.h>
+#ifndef SIMGEAR_HEADLESS
+# include <osg/Vec4>
+#endif
 #include "parse_color.hxx"
 
 #include <boost/algorithm/string/predicate.hpp>

simgear/misc/parse_color.hxx

@@ -23,10 +23,6 @@
 #include <simgear/math/SGMathFwd.hxx>
 #include <simgear/math/SGVec4.hxx>
 
-#ifndef SIMGEAR_HEADLESS
-# include <osg/Vec4>
-#endif
-
 #include <string>
 
 namespace simgear
@@ -42,7 +38,7 @@ namespace simgear
    */
   bool parseColor(std::string str, SGVec4f& result);
 
-#ifndef SIMGEAR_HEADLESS
+#ifdef OSG_VEC4
   /**
    * Parse a (CSS) color into an osg::Vec4
    *