Support :closure-defines in dev builds

[olivergeorge]

Looks like the closure-defines option is not picked up in first build.

Steps to repeat:

• Based on reagent tutorial but using latest git commit (2f4572a)
• Add a goog-define to the core ns and try and try setting it via :closure-define.
• Run iOS app against REPL
• Observe greeting (Hello)
• touch core.cljs
• Observe greeting (G'day)

Expect: greeting is always "G'day Krell"

Actual: Greeting is "Hello Krell" until core.cljs is recompiled.

% cat build.edn
{:main awesome-project.core
 :output-to "target/main.js"
 :output-dir "target"
 :closure-defines {awesome-project.core/greeting "G'day"}}

% cat src/awesome_project/core.cljs
(ns awesome-project.core
  (:require [reagent.core :as r]
            [reagent.react-native :as rn]))

(goog-define greeting "Hello")

(defn ^:export -main [& args]
  (r/as-element
    [rn/view {:style {:flex 1 :align-items "center" :justify-content "center"}}
     [rn/text {:style {:font-size 50}} greeting " Krell!"]]))

[olivergeorge]

Equivalent test using Clojurescript Getting Started guide works.