mesa: enable glx-tls option in native and nativesdk builds
Before meson conversion this was always enabled; now it needs to
be explicitly switched on.
This un-breaks the virgl headless test in particular, which regressed
with the meson conversion (and the test is not currently run on AB
due to oudated graphics hardware in it).
Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
