Re: bootstrap fails on Darwin for `libtool'

[Bruno Haible]

The background appears to be that on macOS:
  * /usr/bin/libtool is an Apple program, that does not support the GNU
    interface. It comes with Xcode; Xcode is the usual way to install a
    C compiler on this platform.
  * To avoid a conflict, people often configure GNU libtool with
    --program-prefix=g.
  * Thus their libtoolize script will be found as 'glibtoolize'.

But AFAICS there is no 'libtoolize' from Apple.

> +      case `uname` in
> +      Darwin*) app=glibtoolize ;;

I would still check to see whether 'libtoolize' exists, before trying
'glibtoolize'. Rationale: 'libtoolize' is the default name, 'glibtoolize'
is just a convention used by many people.

Bruno