meson: try harder to infer build and source directories if called without arguments
meson: try harder to infer build and source directories if called without arguments

If there's no meson.build file in the current directory
and there is one in the parent directory, assume that
we are in the build directory.

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