Fixed osg cmake error.

CMakeLists.txt

@@ -121,8 +121,8 @@ if (UNIX)
     find_package(Flite)
 endif(UNIX)
 find_package(OpenGL REQUIRED)
-find_package(OpenSceneGraph 2.9.9)
-    #COMPONENTS osgGA osgDB osgUtil osgViewer)
+set(OpenSceneGraph_FIND_QUIETLY FALSE)
+find_package(OpenSceneGraph 2.9.9 COMPONENTS osgGA osgDB osgUtil osgViewer)
 find_or_build_from_source(MAVLINK thirdParty/mavlink FOUND_GIT_REPO)
 
 # build libraries from source if not found on system
@@ -196,13 +196,12 @@ else()
     message(STATUS "\t\tMAVLINK\tNO")
 endif ()
 
-message(STATUS "OSG_FOUND: ${OPENSCENEGRAPH_FOUND}")
-if (OPENSCENEGRAPH_FOUND)
+if (${OSG_LIBRARY} STREQUAL "OSG_LIBRARY-NOTFOUND")
+    message(STATUS "\t\tOpenSceneGraph\tNO")
+else()
     message(STATUS "\t\tOpenSceneGraph\tYES")
     list(APPEND qgroundcontrolIncludes ${OPENSCENEGRAPH_INCLUDE_DIRS})
     list(APPEND qgroundcontrolLibs ${OPENSCENEGRAPH_LIBRARIES})
-else()
-    message(STATUS "\t\tOpenSceneGraph\t\tNO")
 endif ()
 
 if (QT4_FOUND)