[Chicken-users] Little fix in svnrevision.sh

[Alonso Andres]

Hello,

I was compiling the hygienic Chicken then at some point a parser error was
displayed.

It was because the constant C_SVN_REVISION was empty, and I've noticed its value
is generated from the "buildsvnrevision" file, which in turn is created by the
script "svnrevision.sh".

This script uses the svn command. But since the locale is configured to my
native language, svn outputs in the current locale and the information can't be
parsed.

This issue was easily fixed by adding the line LANG="C" into the top of
"svnrevision.sh". Maybe this can be useful to someone else who happens to be
using a different locale than English and wants to compile Chicken.

Thanks for working hard on this nice project,

Alonso Andres