redis-tools: set arch explicity

Detection of the build arch is broken on 32-bit Snow Leopard; mirrors
the main redis formula.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/redis-tools.rb

@@ -5,6 +5,8 @@ class RedisTools < Formula
   homepage 'https://github.com/antirez/redis-tools'
 
   def install
+    # Architecture isn't detected correctly on 32bit Snow Leopard without help
+    ENV["OBJARCH"] = MacOS.prefer_64_bit? ? "-arch x86_64" : "-arch i386"
     system "make"
     bin.install ["redis-load", "redis-stat"]
   end