Use "Environment" instead of "Rscons::Environment" in build tests

build_tests/simple_cc/Rsconscript

@@ -1,5 +1,5 @@
 build do
-  Rscons::Environment.new do |env|
+  Environment.new do |env|
     env.Program('simple.exe', Dir['*.cc'])
   end
 end

build_tests/simple_cc/cxxsuffix.rb

@@ -1,5 +1,5 @@
 build do
-  Rscons::Environment.new do |env|
+  Environment.new do |env|
     env["CXXSUFFIX"] = %w[.cccc .cc]
     env["CXXFLAGS"] += %w[-x c++]
     env.Program("simple.exe", Dir["*.cc"] + Dir["*.cccc"])

build_tests/simple_cc/preprocess.rb

@@ -1,5 +1,5 @@
 build do
-  Rscons::Environment.new do |env|
+  Environment.new do |env|
     env.Preprocess("simplepp.cc", "simple.cc")
     env.Program("simple.exe", "simplepp.cc")
   end