* ext/dbm/extconf.rb: duplicate $libs and $defs when save them.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@33732 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Sun Nov 13 15:40:43 2011  Tanaka Akira  <akr@fsij.org>
+
+	* ext/dbm/extconf.rb: duplicate $libs and $defs when save them.
+
 Sun Nov 13 12:43:48 2011  Tanaka Akira  <akr@fsij.org>
 
 	* ext/dbm/extconf.rb: rollback $libs and $defs when db detection is

ext/dbm/extconf.rb

@@ -29,8 +29,8 @@ headers.found = []
 headers.defs = nil
 
 def headers.db_check(db)
-  old_libs = $libs
-  old_defs = $defs
+  old_libs = $libs.dup
+  old_defs = $defs.dup
   result = db_check2(db)
   if !result
     $libs = old_libs