git: build cleanup - add missing build objects to .gitignore

4 jobs for build-am-fix in 3 minutes and 12 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #273848
latest-autotools-lcms

00:03:11

passed #273849
latest-autotools-nolcms

00:03:11

passed #273846
latest-meson-lcms

00:02:26

passed #273847
latest-meson-nolcms

00:02:26