[Dev-luatex] Don't use sed -r

[Yue Wang]

Hi, Taco.

A minor issue: in the file
/src/texk/web2c/luatexdir/get_svnversion.sh, please avoid the -r
option since it is not supported by many sed programs.
see http://www.opengroup.org/onlinepubs/000095399/utilities/sed.html
for the POSIX standard.
(GNU sed support the option, however, BSD style sed (like the one
distributed in FreeBSD or Mac OS X think this is an illegal statement
during compilation)

Yue Wang