test/mkmf/base.rb: use CC_WRAPPER same as the toplevel

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65774 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/mkmf/base.rb

@@ -1,5 +1,13 @@
 # frozen_string_literal: false
 $extmk = true
+require 'rbconfig'
+RbConfig.fire_update!("top_srcdir", File.expand_path("../..", __dir__))
+File.foreach(RbConfig::CONFIG["topdir"]+"/Makefile") do |line|
+  if /^CC_WRAPPER\s*=\s*/ =~ line
+    RbConfig.fire_update!('CC_WRAPPER', $'.strip)
+    break
+  end
+end
 
 require 'test/unit'
 require 'mkmf'