message: cmake: handle VIDEOIO_PLUGIN_LIST=all
diff: -set(VIDEOIO_PLUGIN_LIST "" CACHE STRING "List of videoio backends to be compiled as plugins (ffmpeg, gstreamer)")
  +set(VIDEOIO_PLUGIN_LIST "" CACHE STRING "List of videoio backends to be compiled as plugins (ffmpeg, gstreamer, mfx, msmf or special value 'all')")
  set(VIDEOIO_ENABLE_PLUGINS "ON" CACHE BOOL "Allow building videoio plugin support")
  set(VIDEOIO_ENABLE_STRICT_PLUGIN_CHECK "ON" CACHE BOOL "Make sure OpenCV version is the same in plugin and host code")
  mark_as_advanced(VIDEOIO_PLUGIN_LIST VIDEOIO_ENABLE_PLUGINS VIDEOIO_ENABLE_STRICT_PLUGIN_CHECK)
  @@ -69,7 +69,7 @@ include(${CMAKE_CURRENT_LIST_DIR}/cmake/plugin.cmake)
  set(tgts)
  if(TARGET ocv.3rdparty.mediasdk)
  - if("mfx" IN_LIST VIDEOIO_PLUGIN_LIST)
  + if("mfx" IN_LIST VIDEOIO_PLUGIN_LIST OR VIDEOIO_PLUGIN_LIST STREQUAL "all")
  ocv_create_builtin_videoio_plugin("opencv_videoio_intel_mfx" ocv.3rdparty.mediasdk "cap_mfx_common.cpp" "cap_mfx_reader.cpp" "cap_mfx_writer.cpp" "cap_mfx_plugin.cpp")
  else()
  list(APPEND videoio_srcs
  @@ -91,7 +91,7 @@ if(TARGET ocv.3rdparty.dshow)
  endif()
  if(TARGET ocv.3rdparty.msmf)
  - if("msmf" IN_LIST VIDEOIO_PLUGIN_LIST)
  + if("msmf" IN_LIST VIDEOIO_PLUGIN_LIST OR VIDEOIO_PLUGIN_LIST STREQUAL "all")
  ocv_create_builtin_videoio_plugin("opencv_videoio_msmf" ocv.3rdparty.msmf "cap_msmf.cpp")
  else()
  list(APPEND videoio_srcs ${CMAKE_CURRENT_LIST_DIR}/src/cap_msmf.hpp)
  @@ -111,7 +111,7 @@ if(TARGET ocv.3rdparty.dc1394_2)
  endif()
  if(TARGET ocv.3rdparty.gstreamer)
  - if("gstreamer" IN_LIST VIDEOIO_PLUGIN_LIST)
  + if("gstreamer" IN_LIST VIDEOIO_PLUGIN_LIST OR VIDEOIO_PLUGIN_LIST STREQUAL "all")
  ocv_create_builtin_videoio_plugin("opencv_videoio_gstreamer" ocv.3rdparty.gstreamer "cap_gstreamer.cpp")
  else()
  list(APPEND videoio_srcs ${CMAKE_CURRENT_LIST_DIR}/src/cap_gstreamer.cpp)
  @@ -137,7 +137,7 @@ endif()
  if(TARGET ocv.3rdparty.ffmpeg)
  if(HAVE_FFMPEG_WRAPPER)
  list(APPEND tgts ocv.3rdparty.ffmpeg)
  - elseif("ffmpeg" IN_LIST VIDEOIO_PLUGIN_LIST)
  + elseif("ffmpeg" IN_LIST VIDEOIO_PLUGIN_LIST OR VIDEOIO_PLUGIN_LIST STREQUAL "all")
  ocv_create_builtin_videoio_plugin("opencv_videoio_ffmpeg" ocv.3rdparty.ffmpeg "cap_ffmpeg.cpp")
  else()
  list(APPEND videoio_hdrs ${CMAKE_CURRENT_LIST_DIR}/src/cap_ffmpeg_impl.hpp)
  