package/meson: disable meson wrap downloads

We don't want to allow meson to download wrap dependencies as this
bypasses buildroot's dependency resolution.

This is badly documented in the meson manual, but there is at least
an FAQ that refers to it:

    https://mesonbuild.com/FAQ.html#does-wrap-download-sources-behind-my-back



    Meson has a option called wrap-mode which can be used to disable
    wrap downloads altogether with --wrap-mode=nodownload.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
[yann.morin.1998@free.fr: add pointer to FAQ]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>