Use printf instead of echo -n in bootstrap.sh

The behavior of `echo -n` is not portable and some implementations will
just prtint the literal string "-n".

bootstrap.sh

@@ -42,7 +42,7 @@ fi
 gtkdocize --copy --docdir doc --flavour no-tmpl || exit 1
 
 # some systems need libtoolize, some glibtoolize ... how annoying
-echo -n "testing for glibtoolize ... "
+printf "testing for glibtoolize ... "
 if glibtoolize --version >/dev/null 2>&1; then
   LIBTOOLIZE=glibtoolize
   echo using glibtoolize