Download Redis and flatbuffers differently. (#1602)

* Download Redis differently.

* Get flatbuffers with curl

src/common/thirdparty/build-redis.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+set -x
+
 # Cause the script to exit if a single command fails.
 set -e
 
@@ -9,7 +11,8 @@ if [ ! -f redis/src/redis-server ]; then
   # relevant bit about redis/utils/whatisdoing.sh is that it is one of the last
   # files in the tarball.
   if [ ! -f redis/utils/whatisdoing.sh ]; then
-    mkdir -p "./redis" && wget -O- "https://github.com/antirez/redis/archive/$redis_vname.tar.gz" | tar xvz --strip-components=1 -C "./redis"
+    mkdir -p "./redis"
+    curl -sL "https://github.com/antirez/redis/archive/$redis_vname.tar.gz" | tar xz --strip-components=1 -C "./redis"
   fi
   cd redis
   make