AC_CHECK_HEADER([nettle/sha.h], [], [nettlep=nil])
AC_CHECK_LIB([nettle], [nettle_sha256_init], [], [nettlep=nil])
case $nettlep in
nil) AC_MSG_ERROR([Failed to find Nettle library.]) ;;
esac
AC_CHECK_HEADER([nettle/sha.h], [], [nettlep=nil])
AC_CHECK_LIB([nettle], [nettle_sha256_init], [], [nettlep=nil])
case $nettlep in
nil) AC_MSG_ERROR([Failed to find Nettle library.]) ;;
esac