ninja: Fix build_by_default=false targets in tests
ninja: Fix build_by_default=false targets in tests

Previously, build_by_default=false targets would not be built at all
even if they were used in a test (as the exe or as a command-line
argument) which would lead to a test failure.

Now we look into all the defined tests and add all CustomTargets and
BuildTargets used in them to the list of build_by_default targets.

ernestask/meson,mesonbuild/meson,MathieuDuponchelle/meson,jeandet/meson,pexip/meson,ernestask/meson,ernestask/meson,mesonbuild/meson,fmuellner/meson,rhd/meson,QuLogic/meson,mesonbuild/meson,rhd/meson,pexip/meson,QuLogic/meson,thiblahute/meson,wberrier/meson,wberrier/meson,thiblahute/meson,thiblahute/meson,mesonbuild/meson,jpakkane/meson,becm/meson,rhd/meson,fmuellner/meson,wberrier/meson,aaronp24/meson,becm/meson,pexip/meson,jeandet/meson,wberrier/meson,aaronp24/meson,QuLogic/meson,MathieuDuponchelle/meson,pexip/meson,mesonbuild/meson,fmuellner/meson,aaronp24/meson,thiblahute/meson,becm/meson,aaronp24/meson,becm/meson,MathieuDuponchelle/meson,jpakkane/meson,pexip/meson,thiblahute/meson,ernestask/meson,QuLogic/meson,becm/meson,QuLogic/meson,rhd/meson,jeandet/meson,jpakkane/meson,fmuellner/meson,wberrier/meson,aaronp24/meson,wberrier/meson,thiblahute/meson,aaronp24/meson,MathieuDuponchelle/meson,MathieuDuponchelle/meson,QuLogic/meson,jpakkane/meson,trhd/meson,trhd/meson,jpakkane/meson,ernestask/meson,rhd/meson,rhd/meson,jpakkane/meson,wberrier/meson,mesonbuild/meson,jeandet/meson,trhd/meson,becm/meson,becm/meson,becm/meson,ernestask/meson,rhd/meson,becm/meson,fmuellner/meson,mesonbuild/meson,rhd/meson,trhd/meson,QuLogic/meson,wberrier/meson,fmuellner/meson,thiblahute/meson,aaronp24/meson,MathieuDuponchelle/meson,jeandet/meson,QuLogic/meson,fmuellner/meson,fmuellner/meson,trhd/meson,jpakkane/meson,jpakkane/meson,jeandet/meson,MathieuDuponchelle/meson,fmuellner/meson,aaronp24/meson,trhd/meson,pexip/meson,MathieuDuponchelle/meson,jeandet/meson,mesonbuild/meson,jpakkane/meson,mesonbuild/meson,becm/meson,MathieuDuponchelle/meson,mesonbuild/meson,jeandet/meson,ernestask/meson,pexip/meson,thiblahute/meson,QuLogic/meson,jeandet/meson,trhd/meson,trhd/meson,pexip/meson,aaronp24/meson,ernestask/meson,pexip/meson,trhd/meson,thiblahute/meson,ernestask/meson,pexip/meson