[Bug other/102664] contrib/gcc-git-customization.sh uses echo -n, which isn't portable

[rearnsha at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102664

--- Comment #29 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Suggested patch:
https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591455.html