Having 'cat' use copy_file_range

[Paul Eggert]

cp+install+mv started using copy_file_range in coreutils 9.0 and it 
seems to be working OK, so I thought I'd change cat to use it too. While 
looking into that I found some infelicities and/or unlikely integer 
overflows to fix (of course there are more where these came from; these 
are just the ones having to do with page-aligned buffer allocation which 
is something cat does).

I installed the attached series of patches to do all that; the last 
patch is the copy_file_range change.

0001-cat-improve-style.patch
Description: Text Data

0002-cat-prefer-signed-to-unsigned.patch
Description: Text Data

0003-shred-fix-declaration-typo.patch
Description: Text Data

0004-dd-improve-integer-overflow-checking.patch
Description: Text Data

0005-dd-simplify-conv-swab-code.patch
Description: Text Data

0006-copy-remove-unnecessary-free.patch
Description: Text Data

0007-build-update-gnulib-submodule-to-latest.patch
Description: Text Data

0008-maint-simplify-memory-alignment.patch
Description: Text Data

0009-csplit-improve-integer-overflow-checking.patch
Description: Text Data

0010-cat-prefer-copy_file_range-to-read-write.patch
Description: Text Data