gnome: Filter LDFLAGS passed to g-ir-scanner
gnome: Filter LDFLAGS passed to g-ir-scanner

g-ir-scanner is very picky about the flags that it can accept, so the
build fails on macOS if you have Framework external dependencies,
which add -F and -framework arguments.

Also fix incorrect de-duping of -framework arguments for gtkdoc.

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