configure.in: unquote

* configure.in (LIBDIR_BASENAME): unquote shell variable.
  [ruby-core:47267] [Bug #6903]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36873 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -2574,7 +2574,7 @@ AS_CASE("$enable_shared", [yes], [
   if test "$bindir" = '${exec_prefix}/bin'; then
     AS_CASE(["$libdir"], ['${exec_prefix}/'*], [libdir_basename=`basename "$libdir"`])
   fi
-  AC_DEFINE(LIBDIR_BASENAME, ["${libdir_basename}"])
+  AC_DEFINE_UNQUOTED(LIBDIR_BASENAME, ["${libdir_basename}"])
 
   AS_CASE(["$target_os"],
     [freebsd*|dragonfly*], [],