* file.c (rb_sys_fail_path0): add to append the name of called function
  to ease debugging for example blow umask_spec failure.
  http://fbsd.rubyci.org/~chkbuild/ruby-trunk/log/20130309T010202Z.diff.html.gz

* file.c (rb_sys_fail_path): use rb_sys_fail_path0.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39752 b2dd03c8-39d4-4d8f-98ff-823fe69b080e