find_dependency TIFF & PNG

add missing find_dependency for TIFF and PNG

Author: Ubiquite

cmake/templates/OpenCVConfig.cmake.in

@@ -367,3 +367,9 @@ include(CMakeFindDependencyMacro)
 if("@JPEG_FOUND@")
   find_dependency(JPEG CONFIG)
 endif()
+if("@TIFF_FOUND@")
+  find_dependency(TIFF CONFIG)
+endif()
+if("@PNG_FOUND@")
+  find_dependency(PNG CONFIG)
+endif()