xorg: Don't log "Build Operating System: Linux 4.9.0-5-amd64 x86_64 Debian"

I don't think this is useful information to have in the log, and it's
a bunch of autotools and meson logic to produce it.

Signed-off-by: Eric Anholt <eric@anholt.net>
1 job for no-builder-in-log in 1 minute and 31 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
passed job #24231

00:01:31