rpm: use VPATH macro
rpm: use VPATH macro

This is more or less standardized way to have one variable which
will work for all buildsystems defined in redhat-rpm-config.

Signed-off-by: Igor Gnatenko <c869b0bfe2cf1da26c2efd33f6d6d74ddcbbdd2b@gmail.com>

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