Better error message when using external libraries incorrectly. Closes #2447.
Better error message when using external libraries incorrectly. Closes #2447.

thiblahute/meson,pexip/meson,QuLogic/meson,pexip/meson,QuLogic/meson,thiblahute/meson,ernestask/meson,trhd/meson,jpakkane/meson,ernestask/meson,ernestask/meson,MathieuDuponchelle/meson,thiblahute/meson,pexip/meson,becm/meson,mesonbuild/meson,pexip/meson,becm/meson,mesonbuild/meson,MathieuDuponchelle/meson,trhd/meson,jpakkane/meson,trhd/meson,pexip/meson,QuLogic/meson,thiblahute/meson,jeandet/meson,MathieuDuponchelle/meson,MathieuDuponchelle/meson,mesonbuild/meson,becm/meson,QuLogic/meson,trhd/meson,ernestask/meson,trhd/meson,jeandet/meson,trhd/meson,jpakkane/meson,becm/meson,trhd/meson,trhd/meson,mesonbuild/meson,becm/meson,jeandet/meson,thiblahute/meson,pexip/meson,QuLogic/meson,mesonbuild/meson,becm/meson,ernestask/meson,becm/meson,becm/meson,jpakkane/meson,mesonbuild/meson,thiblahute/meson,QuLogic/meson,jpakkane/meson,jeandet/meson,QuLogic/meson,ernestask/meson,MathieuDuponchelle/meson,ernestask/meson,thiblahute/meson,mesonbuild/meson,MathieuDuponchelle/meson,jpakkane/meson,mesonbuild/meson,trhd/meson,jeandet/meson,jeandet/meson,thiblahute/meson,MathieuDuponchelle/meson,jeandet/meson,pexip/meson,mesonbuild/meson,pexip/meson,MathieuDuponchelle/meson,jpakkane/meson,thiblahute/meson,ernestask/meson,mesonbuild/meson,jeandet/meson,jpakkane/meson,QuLogic/meson,MathieuDuponchelle/meson,pexip/meson,becm/meson,QuLogic/meson,pexip/meson,jeandet/meson,ernestask/meson,becm/meson,jpakkane/meson