COMP: the variable to be used for gdal includes is GDAL_INCLUDE_DIRS not GDAL_INCLUDE_DIR

CMake/otbIncludeDirectories.cmake

@@ -68,7 +68,7 @@ ELSE(OTB_USE_EXTERNAL_BOOST)
 ENDIF(OTB_USE_EXTERNAL_BOOST)
 
 SET(OTB_INCLUDE_DIRS_BUILD_TREE ${OTB_INCLUDE_DIRS_BUILD_TREE}
-    ${GDAL_INCLUDE_DIR} )
+    ${GDAL_INCLUDE_DIRS} )
 
 IF(WIN32)
   SET(OTB_INCLUDE_DIRS_BUILD_TREE ${OTB_INCLUDE_DIRS_BUILD_TREE}