Fix OpenJPEG version in cmake scripts

Currently, if OpenJPEG is found, only version information in summary is
correct and the information right after `find_package(OpenJPEG)` is
wrong.
```
-- Found system OpenJPEG: openjp2 (found version "")
```

The reason is OpenJPEGConfig.cmake only sets `OPENJPEG_MAJOR_VERSION`,
`OPENJPEG_MINOR_VERSION` and `OPENJPEG_BUILD_VERSION` but not `OPENJPEG_VERSION`.

CMakeLists.txt

@@ -1415,7 +1415,7 @@ endif()
 
 if(HAVE_OPENJPEG)
   status("    JPEG 2000:" OpenJPEG_FOUND
-      THEN "OpenJPEG (ver ${OPENJPEG_MAJOR_VERSION}.${OPENJPEG_MINOR_VERSION}.${OPENJPEG_BUILD_VERSION})"
+      THEN "OpenJPEG (ver ${OPENJPEG_VERSION})"
       ELSE "build (ver ${OPENJPEG_VERSION})"
   )
 elseif(HAVE_JASPER)

cmake/OpenCVFindLibsGrfmt.cmake

@@ -202,6 +202,7 @@ if(WITH_OPENJPEG)
     endif()
   else()
     set(HAVE_OPENJPEG YES)
+    set(OPENJPEG_VERSION "${OPENJPEG_MAJOR_VERSION}.${OPENJPEG_MINOR_VERSION}.${OPENJPEG_BUILD_VERSION}")
     message(STATUS "Found system OpenJPEG: ${OPENJPEG_LIBRARIES} "
             "(found version \"${OPENJPEG_VERSION}\")")
   endif()