ghostscript: never use autorotatepages

It looks like from the gs manual that this parameter is only respected for
vector devices so it never had any effect, but to stay on the safe side,
which it off.

src/ocrmypdf/exec/ghostscript.py

@@ -113,8 +113,6 @@ def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log,
     if not page_dpi:
         page_dpi = res
 
-    autorotate = '/PageByPage' if rotation is None else '/None'
-
     with NamedTemporaryFile(delete=True) as tmp:
         args_gs = [
             'gs',
@@ -127,7 +125,7 @@ def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log,
             '-dLastPage=%i' % pageno,
             '-r{0}x{1}'.format(str(int_res[0]), str(int_res[1])),
             '-o', tmp.name,
-            '-dAutoRotatePages=%s' % autorotate,
+            '-dAutoRotatePages=/None',  # Probably has no effect on raster
             '-f',
             fspath(input_file)
         ]