The bind-tools-9.4.0 package can't be emerged on g/fbsd (with idn use flag enabled) due to a failure in the contrib/idn/idnkit-1.0-src configure script (config.log attached) whose cause seems to be a missing "-liconv" in the gcc command used to compile the conftest. It seems that the simplest solution to the problem consists in adding "--with-iconv=/usr/$(get_libdir)/libiconv.so" to the idn econf arguments list in the ebuild.
Created attachment 113367 [details] modified ebuild - the econf argument required for compilation under g/fbsd is added conditionally with a test on CHOST (inspired by unzip ebuild)
Created attachment 113369 [details] config.log from the failing configure script
Fixed, thanks