io.c: remove unnecessary shared

* io.c (rb_io_reopen): FilePathValue() ensures the path
  NUL-terminated and frozen, so it is unnecessary to make it shared.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51074 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Tue Jun 30 23:12:08 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (rb_io_reopen): FilePathValue() ensures the path
+	  NUL-terminated and frozen, so it is unnecessary to make it shared.
+
 Tue Jun 30 23:11:53 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* dir.c (check_dirname): ensure path name NUL-terminated for

io.c

@@ -6778,7 +6778,7 @@ rb_io_reopen(int argc, VALUE *argv, VALUE file)
 	oflags = rb_io_fmode_oflags(fptr->mode);
     }
 
-    fptr->pathv = rb_str_new_frozen(fname);
+    fptr->pathv = fname;
     if (fptr->fd < 0) {
         fptr->fd = rb_sysopen(fptr->pathv, oflags, 0666);
 	fptr->stdio_file = 0;