Don't support the latest flymake

I encounter an error when I type `M-x helm-flymake`, here is the backtrace

> Debugger entered--Lisp error: (void-variable flymake-err-info)
> helm-flymake-get-err-list()
> helm-flymake-get-err-list-sorted()
> helm-flymake-get-candidate("w")
> helm-flymake-init("w")
> (lambda nil (helm-flymake-init "w"))()
> apply((lambda nil (helm-flymake-init "w")) nil)
> helm-funcall-with-source(((name . "Flymake Warning") (init lambda nil (helm-flymake-init "w")) (candidates-in-buffer) (candidate-transformer lambda (cands) (delete "" cands)) (type . line) (action ("Goto Line" . helm-flymake-action-goto-line)) (recenter)) (lambda nil (helm-flymake-init "w")))
> helm-funcall-foreach(init)
> helm-initial-setup(nil)
> helm-initialize(nil nil nil (helm-source-flymake-warning helm-source-flymake-error))
> helm-internal((helm-source-flymake-warning helm-source-flymake-error) nil nil nil nil # nil nil nil)
> apply(helm-internal ((helm-source-flymake-warning helm-source-flymake-error) nil nil nil nil # nil nil nil))
> helm((helm-source-flymake-warning helm-source-flymake-error) nil nil nil nil # nil nil nil)
> apply(helm ((helm-source-flymake-warning helm-source-flymake-error) nil nil nil nil # nil nil nil))
> helm(:sources (helm-source-flymake-warning helm-source-flymake-error) :buffer # :input nil)
> helm-flymake(nil)
> funcall-interactively(helm-flymake nil)
> call-interactively(helm-flymake record nil)
> command-execute(helm-flymake record)
> helm-M-x(nil #("helm-flymake" 0 12 (match-part "helm-flymake")))
> funcall-interactively(helm-M-x nil #("helm-flymake" 0 12 (match-part "helm-flymake")))
> call-interactively(helm-M-x nil nil)
> command-execute(helm-M-x)
>

I built my Emacs from git repo recently. The variable `flymake-err-info` was removed a few months ago in https://github.com/emacs-mirror/emacs/commit/94a88c1ae98b1bf7ab80ae9cdd4d6e16b36597ef. I think I can fix this issue when I have time and get familiar with flymake.

Start at helm-flymake-get-err-list, which the backtrace identifies as the failing entry point, and compare its use of flymake-err-info with the Flymake change in commit 94a88c1ae98b1bf7ab80ae9cdd4d6e16b36597ef. The work is done when M-x helm-flymake no longer raises the void-variable error with the latest Flymake.

Written by the indexing model from the issue text.