compilers: Don't pollute c_args with -fPIC on OS X
compilers: Don't pollute c_args with -fPIC on OS X

It's always enabled and the compiler just ignores all PIC-related
arguments. Relatedly, do the same thing for Clang as GCC.

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