dependencies: Use a wrapper for calling pkg-config
dependencies: Use a wrapper for calling pkg-config

Reduces duplicated code, and also use universal_newlines=True which
avoids having to decode the bytes output to string.

We mostly need this so we can pass the *current* process environment to
pkg-config which might've changed since the module was imported. Without
this, subprocess.Popen invokes pkg-config with a stale environment (used
in the unittest added later)

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