Add dash to `--without $feature` for consistency in the help output

[pcrama]

emacs-build/emacs-build.sh

Line 58 in b29b161

for f in $inactive; do echo " --without $f"; done

would be better written as

    for f in $inactive; do echo "  --without-$f"; done

Otherwise the emacs-build.sh --help output looks odd (notice the missing dash in the last line when comparing with the lines above):

Emacs-build tool version 0.4.1, (c) 2020 Juan Jose Garcia-Ripoll
Usage:
... 8< snip 8< snip 8< ...
  --with-gnutls
  --with-zlib
  --without native-compilation