Fix last change on 'compilation-parse-errors'

* lisp/progmodes/compile.el (compilation-parse-errors): Fix
previous change in this function.  (Bug#34479)

Copyright-paperwork-exempt: yes
1 job for emacs-26 in 60 minutes and 1 second (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #931
test

01:00:01

 
Name Stage Failure
failed
test Test The script exceeded the maximum execution time set for the job

In end of data:
lisp/net/shr-tests.el:59:1:Warning: the function `libxml-parse-html-region' is
not known to be defined.
GEN lisp/net/shr-tests.log
ELC lisp/net/tramp-tests.elc
GEN lisp/net/tramp-tests.log
Pulling docker image gitlab/gitlab-runner-helper:x86_64-f100a208 ...
ERROR: Job failed: execution took longer than 1h0m0s seconds