external/libsodium: remove

We shipped our own because Ubuntu xenial (16.4) had an ancient one.

Changelog-Changed: Build: libsodium version >= 1.0.4 now required (released 2015-06-11)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

.github/scripts/setup.sh

@@ -30,6 +30,7 @@ sudo apt-get -qq install --no-install-recommends --allow-unauthenticated -yy \
      libicu-dev \
      libpq-dev \
      libprotobuf-c-dev \
+     libsodium-dev \
      libsqlite3-dev \
      libssl-dev \
      libtool \

.github/workflows/bsd.yml

@@ -40,6 +40,7 @@ jobs:
             bash \
             gettext \
             sqlite3 \
+            libsodium \
             lowdown \
             pkgconf \
             jq \
@@ -60,7 +61,7 @@ jobs:
           git clone https://github.com/lightning/bolts.git ../bolts
           # fatal: unsafe repository ('/Users/runner/work/lightning/lightning' is owned by someone else)
           git config --global --add safe.directory `pwd`
-          for d in libsodium libwally-core gheap jsmn libbacktrace; do git config --global --add safe.directory `pwd`/external/$d; done
+          for d in libwally-core gheap jsmn libbacktrace; do git config --global --add safe.directory `pwd`/external/$d; done
           git submodule update --init --recursive
 
           ./configure CC="$CC" --disable-valgrind

.github/workflows/macos.yaml

@@ -37,7 +37,7 @@ jobs:
         run: |
           export PATH="/usr/local/opt:/Users/runner/.local/bin:/opt/homebrew/bin/python3.10/bin:$PATH"
 
-          brew install gnu-sed autoconf automake libtool protobuf openssl lowdown
+          brew install gnu-sed autoconf automake libtool protobuf openssl lowdown libsodium
 
           # https://github.com/grpc/grpc/issues/31737#issuecomment-1323796842
           export GRPC_PYTHON_BUILD_SYSTEM_OPENSSL=1