meson: provide relocation script and native/cross wrappers also for meson-native

meson: provide relocation script and native/cross wrappers also for meson-native

When using meson-native directly from bitbake this has no effect and
everything works as before; the use case is being able to build
meson-driven projects from the 'direct SDK' environment. Build systems
like cmake/autotools are entirely driven by environment variables,
but meson needs configuration files, and so this replicates how SDKs
set things up.

In particular, with this change the libepoxy build test from the SDK
test suite is able to pass.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>