sed error (illegal byte sequence) at sudo make install concerning Ddd.ad.h under mac OS X

Hello,

I am using GNU gcc-5.2's gcc and g++ in what follows, and I am under mac os
x yosemite.

I configured lesstif-0.95.2 with

./configure --prefix=/usr/local/lvm/lesstif-0.95.2

and then make -j 4 and sudo make install. Had only a problem with

/usr/local/lvm/lesstif-0.95.2/include/Motif-2.1/Xm/Xm.h.in

that contained two strange "diamond-like" characters in its beginning and
commented copyright part that I replaced with "C"'s.

After I configured ddd-3.3.12 with :

./configure --with-motif-includes=/usr/local/lvm/lesstif-0.95.2/include/
--with-motif-libraries=/usr/local/lvm/lesstif-0.95.2/lib/

Then I make -j 4 and then I sudo make install and got this error :

cat Ddd | cat | \

/usr/bin/sed -n -f ./ad2c.sed > Ddd.ad.h~ && mv Ddd.ad.h~ Ddd.ad.h

sed: RE error: illegal byte sequence

make[1]: *** [Ddd.ad.h] Error 1

make: *** [install-recursive] Error 1

How could I correct it ?

Thx in advance,

Christian