os: Always create lock file on explicit display

I.e., even if "-displayfd" is also specified. This is because, in this case,
the server creation process is essentially the same as when "-displayfd" is not
specified. The only difference with the latter case should be that Xorg outputs
the passed display to the display FD (only the display selection logic is
bypassed).

Signed-off-by: Olivier Certner <olce.freedesktop@certner.fr>
4 jobs for issue-1139 in 4 minutes and 24 seconds (queued for 2 seconds)
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Status Name Job ID Coverage
  Docker Image
passed debian-buster #7322233

00:00:12

 
  Build And Test
passed autotools #7322234

00:04:11

passed meson #7322235

00:02:09

passed meson-noglamor #7322236

00:03:07