Add libsodium to the tree and build what's needed from source.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3859 ed5197a5-7fde-0310-b194-c3ffbd925b24

deps/libsodium/dist-build/msys2-win64.sh

@@ -0,0 +1,18 @@
+#! /bin/sh
+
+export CFLAGS="-Ofast -fomit-frame-pointer -m64 -mtune=westmere"
+export PREFIX="$(pwd)/libsodium-win64"
+
+if (x86_64-w64-mingw32-gcc --version > /dev/null 2>&1) then
+  echo MinGW found
+else
+  echo Please install mingw-w64-x86_64-gcc >&2
+  exit
+fi
+
+./configure --prefix="$PREFIX" --exec-prefix="$PREFIX" \
+            --host=x86_64-w64-mingw32 && \
+make clean && \
+make && \
+make check && \
+make install