message: build, qt: Always test plugins/subdir before adding to search paths
  The existence of each subdir is not guaranteed for all platforms.
diff: @@ -123,7 +123,12 @@ AC_DEFUN([BITCOIN_QT_CONFIGURE],[
  _BITCOIN_QT_CHECK_STATIC_LIBS
  if test "x$qt_plugin_path" != x; then
  - QT_LIBS="$QT_LIBS -L$qt_plugin_path/platforms -L$qt_plugin_path/styles"
  + if test -d "$qt_plugin_path/platforms"; then
  + QT_LIBS="$QT_LIBS -L$qt_plugin_path/platforms"
  + fi
  + if test -d "$qt_plugin_path/styles"; then
  + QT_LIBS="$QT_LIBS -L$qt_plugin_path/styles"
  + fi
  if test -d "$qt_plugin_path/accessible"; then
  QT_LIBS="$QT_LIBS -L$qt_plugin_path/accessible"
  fi
  