fix FTBFS, error: ‘dup’ was not declared in this scope #94

I get FTBFS with this error:

../kimgio/jp2.cpp: In function ‘void kimgio_jp2_write(TQImageIO*)’:
../kimgio/jp2.cpp:249:31: error: ‘dup’ was not declared in this scope
  249 |   stream = jas_stream_fdopen( dup( qf->handle() ), "w" );
      |                               ^~~
../kimgio/jp2.cpp:253:31: error: ‘dup’ was not declared in this scope
  253 |   stream = jas_stream_fdopen( dup( ktempf->handle()), "w" );
      |                               ^~~
[2271/2828] Building CXX object kimgio/CMakeFiles/kimg_exr-module.dir/exr.cpp.o

I didn't have any FTBFS in Debian, but I guess it doesn't hurt to merge this since you were having the problem. Thanks!