Byte order mark always make some files modified

[Chenxiong Qi]

Hi,

Following files are always marked as modified in my repos when swtich
between maint and master back and forth, sometimes these modified
files prevent git from git-checkout, meanwhile they cannot be stashed
or checked out with `checkout --`.

modified:   doc/README-de.win32-bin.txt
modified:   doc/README-fr.win32-bin.txt
modified:   doc/README-it.win32-bin.txt
modified:   doc/README-nl.win32-bin.txt
modified:   doc/README-zh_CN.win32-bin.txt
modified:   doc/README-zh_TW.win32-bin.txt
modified:   doc/README.win32-bin.txt
modified:   doc/examples/downloaded.mt940

I searched archived mails in gnucash-devel, set `git config --global
core.autocrlf input`. However, this only affects the first time when
checkout branch from master to maint. Above issue happens again when
checkout back to master from maint. Really confused, have no idea why
this happens and not sure whether it's an CRLF-related issue.

-- 
Regards,
Chenxiong Qi