meson.build: whitespace fixes

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
2 jobs for master in 2 minutes and 22 seconds (queued for 1 second)
Status Name Job ID Coverage
  Prep
passed container-prep #2721861

00:01:50

 
  Test
passed test #2721862

00:00:32