As of slibtool commit 9c5ba5eb, scute now builds out of the box. I'd still recommend taking the above into consideration, though.

For what it's worth, scute is in violation of gnu libtool's documentation. Building with gnu libtool:

In T5394#145082, @werner wrote:

Regarding slibtool: I would actually like to have an easier to maintain tool than libtool (of which we use our own version) for GnuPG related software. However, its requirement "the compiler should support -std=c99" is currently a no-starter for libgcrypt and some other libs.