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/test/constcheck.sh

@@ -0,0 +1,20 @@
+#! /bin/sh
+
+CT='ct.c'
+
+echo '#include <assert.h>' > "$CT"
+echo '#include <sodium.h>' >> "$CT"
+echo 'int main(void) {' >> "$CT"
+for macro in $(egrep -r '#define crypto_.*BYTES(_[A-Z]+)? ' src/libsodium/include | \
+               cut -d: -f2- | cut -d' ' -f2 | \
+               fgrep -v edwards25519sha512batch | sort -u); do
+  func=$(echo "$macro" | tr A-Z a-z)
+  echo "    assert($func() == $macro);" >> "$CT"
+done
+echo "return 0; }" >> "$CT"
+
+CPPFLAGS="${CPPFLAGS} -Wno-deprecated-declarations"
+${CC:-cc} "$CT" $CPPFLAGS $CFLAGS $LDFLAGS -lsodium || exit 1
+./a.out || exit 1
+rm -f a.out "$CT"
+