net-misc/curl-7.21.1[gnutls,ssl] fails to build with >=net-libs/gnutls-2.11.1[nettle], because then libgnutls.so isn't linked against libgcrypt.so.
Created attachment 247481 [details] curl-7.21.1:20100915-153415.log
I've reported the issue upstream.
Created attachment 248229 [details, diff] Patch from upstream git This is the temporary solution upstream used. The patch adds a configure check for libgcrypt when using gnutls, and thus appends libgcrypt flags.
Created attachment 248231 [details, diff] Complete ebuild patch This is a complete patch to fix the current ebuild to work with gnutls[nettle].
Fixed fully in 7.21.4