osgeo4w: fix starting of qt5 designer

jef-n · jef-n · commit bd0667c480e8 · 2019-03-29T21:47:03.000+01:00
(cherry picked from commit b9a53d4)
diff --git a/ms-windows/osgeo4w/designer.bat.tmpl b/ms-windows/osgeo4w/designer.bat.tmpl
@@ -5,4 +5,4 @@ call py3_env.bat
 path %OSGEO4W_ROOT%\apps\@package@\bin;%PATH%
 set QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/@package@
 set QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\@package@\qtplugins;%OSGEO4W_ROOT%\apps\qt5\plugins
-start "Qt Designer with QGIS custom widgets" /B designer.exe %*
+start "Qt Designer with QGIS custom widgets" /B "%OSGEO4W_ROOT%\apps\qt5\bin\designer.exe" %*
