[iOS Ext] Always pass on the full env to the target.

NEWS

@@ -1,5 +1,7 @@
 = RubyMotion 3.1 =
 
+  * [iOS] Fixed a refression that made it impossible to set environment
+    variables from a host application and propagate them to extensions.
   * [iOS] Fixed a regression that made extensions crash at startup.
   * [iOS] Fixed a regression where a wrong info.plist would be generated which
     related to Background Fetch.

lib/motion/project/target.rb

@@ -135,8 +135,9 @@ module Motion; module Project
       end
     end
 
-    # @return [Hash] The environment variables that describes the current host
-    #         application and which the target's build system depends on.
+    # @return [Hash] The current environment variables onto which the variables
+    #         that describe the current host application are merged, which the
+    #         target's build system depends on.
     #
     def environment_variables
       env = {
@@ -151,7 +152,7 @@ module Motion; module Project
         "RM_TARGET_ARCHS" => @config.archs.inspect,
       }
       env["BUNDLE_GEMFILE"] = gemfile_path if use_gemfile?
-      env
+      ENV.to_hash.merge(env)
     end
 
     # --------------------------------------------------------------------------