Created attachment 309327 [details, diff] curl-7.25.0-r1.ebuild.patch net-misc/curl-7.25.0-r1 contains some code related to net-libs/gnutls. >=net-libs/gnutls-3 supports only Nettle, so it doesn't have "nettle" USE flag. I'm attaching the patch.
Fixed. BTW, gnutls-3 does not autoreconf with autoconf-2.68. It is AC_PREREQ(2.61).
autotools.eclass contains: if [[ -n ${WANT_AUTOCONF} ]] ; then case ${WANT_AUTOCONF} in none) _autoconf_atom="" ;; # some packages don't require autoconf at all 2.1) _autoconf_atom="=sys-devel/autoconf-${WANT_AUTOCONF}*" ;; # if you change the "latest" version here, change also autotools_env_setup latest|2.5) _autoconf_atom=">=sys-devel/autoconf-2.68" ;; *) die "Invalid WANT_AUTOCONF value '${WANT_AUTOCONF}'" ;; esac export WANT_AUTOCONF fi