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

["egallager at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

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

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |iains at gcc dot gnu.org,
                   |                            |jakub at gcc dot gnu.org

--- Comment #6 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Martin Liška from comment #5)
> (In reply to Eric Gallager from comment #3)
> > Along these lines, there's also some non-portable usage of `expr` in the
> > file, too (which I brought up on IRC), but I forget what exactly it was...
> 
> Do you know what exactly is problematic regarding the portability?

Ah, I found my IRC log; apparently it was the `expr match` part:

 1635762461 31<egallager>30     hm, looks like I need to use gexpr instead of
just-plain expr
T 1635762474 31<egallager>30    I guess it's a GNU vs. BSD thing 
T 1635762672 31<egallager>30    so I guess that's a separate bug to file
T 1635762691 31<egallager>30    I guess the g:hash syntax will do for now for
the other one I was filing 
T 1635762767 18<iains>  yes, there are some non-portable parts in the
customisation … 
T 1635762803 18<jakub>  expr is used twice there, is the problem with expr
match or with expr x - y
T 1635762865 18*        iains thought the initial problem was with the match ..
but ICBW
T 1635762967 18<jakub>  I guess it can be replaced with echo | grep -q too, but
for bash that is unnecessary slowdown...; perhaps gcc-git-customization.sh
could check if expr match works and if not, use something different...
T 1635763046 31<egallager>30    I think it's the expr match part