Enable DoH in dnsdist package

dnsdist 1.4+ supports DoH but it needs enabling at build time. Please add h2o-dev wslay-dev as build deps, --enable-dns-over-https and a configure parameter and that should be enough.

However, due to a bug in libh2o-evloop pkgconfig you need to export LIBH2OEVLOOP_LIBS="-lh2o-evloop -lwslay" to the configure command to get it linking properly.

Have tested this locally against alpine 3.11 and builds fine.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information