BUG: Qt5 components not correctly detected if only Qt5_DIR is provided, when this is supported by Qt CMake system.

Fixed by updating Qt5 find_package call to use modern CMake syntax

cmake/OpenCVFindLibsGUI.cmake

@@ -15,15 +15,11 @@ endif()
 ocv_clear_vars(HAVE_QT HAVE_QT5)
 if(WITH_QT)
   if(NOT WITH_QT EQUAL 4)
-    find_package(Qt5Core)
-    find_package(Qt5Gui)
-    find_package(Qt5Widgets)
-    find_package(Qt5Test)
-    find_package(Qt5Concurrent)
-    if(Qt5Core_FOUND AND Qt5Gui_FOUND AND Qt5Widgets_FOUND AND Qt5Test_FOUND AND Qt5Concurrent_FOUND)
+    find_package(Qt5 COMPONENTS Core Gui Widgets Test Concurrent REQUIRED NO_MODULE)
+    if(Qt5_FOUND)
       set(HAVE_QT5 ON)
       set(HAVE_QT  ON)
-      find_package(Qt5OpenGL)
+      find_package(Qt5 COMPONENTS OpenGL QUIET)
       if(Qt5OpenGL_FOUND)
         set(QT_QTOPENGL_FOUND ON)
       endif()