Add install_umask to list of options of `meson configure`
Add install_umask to list of options of `meson configure`

Tested:

  $ ./meson.py configure --help
  [...]
    --install-umask INSTALL_UMASK
                          Default umask to apply on permissions of installed
                          files (default: 022).

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