vcl: Drop unused include from fftester

Change-Id: Iebb02463af8ca9aaa14c7128ff0528184a061b7e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/208632
Reviewed-by: Khaled Hosny <khaled@libreoffice.org>
Tested-by: Jenkins

vcl/workben/fftester.cxx

@@ -68,7 +68,6 @@
 #include <rtl/bootstrap.hxx>
 #include <tools/stream.hxx>
 #include <vcl/gdimtf.hxx>
-#include <fontsubset.hxx>
 
 #include "../source/filter/igif/gifread.hxx"
 #include "../source/filter/ixbm/xbmread.hxx"