bug#29187: flymake ruby and perl tests fail on rhel7.4

[Glenn Morris]

Package: emacs
Version: 26.0.90

Hi,

The flymake tests added in 58bb346 for Ruby and Perl fail on RHEL7.4.
I guess it's again due to different versions of an external tool
reporting errors/warnings differently.

perl version: v5.16.3
ruby version: 2.0.0p648

Test perl-backend condition:
    (ert-test-failed
     ((should
       (eq 'flymake-error
           (face-at-point)))
      :form
      (eq flymake-error flymake-warning)
      :value nil))
   FAILED  4/8  perl-backend

Test ruby-backend condition:
    (ert-test-failed
     ((should
       (eq 'flymake-warning
           (face-at-point)))
      :form
      (eq flymake-warning nil)
      :value nil))
   FAILED  6/8  ruby-backend