mkmf.rb: set cxxflags

* lib/mkmf.rb (configuration): set the default cxxflags, which is
  referred from the default CXXFLAGS, for extension libraries.
  [Fix GH-823]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49476 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Tue Feb  3 12:26:35 2015  Katsuhiko Nishimra  <ktns.87@gmail.com>
+
+	* lib/mkmf.rb (configuration): set the default cxxflags, which is
+	  referred from the default CXXFLAGS, for extension libraries.
+	  [Fix GH-823]
+
 Tue Feb  3 05:52:00 2015  Aman Gupta <ruby@tmm1.net>
 
 	* gc.c (rb_objspace_free): cause rb_bug if lazy sweep is in progress

lib/mkmf.rb

@@ -1928,6 +1928,7 @@ COUTFLAG = #{COUTFLAG}$(empty)
 
 RUBY_EXTCONF_H = #{$extconf_h}
 cflags   = #{CONFIG['cflags']}
+cxxflags = #{CONFIG['cxxflags']}
 optflags = #{CONFIG['optflags']}
 debugflags = #{CONFIG['debugflags']}
 warnflags = #{$warnflags}