package/pkg-meson: force-disable binary stripping

In buildroot, stripping for the target is configured and implemented
with the global `BR2_STRIP_strip` option that drive the stripping in
the target-finalize step.

So, we explicitly disable stripping at build time for the target
variants.

For the host variants, however, we don't much care about symbols and
stuff, but smaller executables will hopefully load faster than bigger
ones (disputable, given that sections in ELF files are paged-in
on-demand), so we explictly enable stripping.

Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
[yann.morin.1998@free.fr:
  - add burb about the target-finalize step
  - enable stripping for host variants
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>