meson: Add missing inc's to idep_nir_headers
What does this MR do and why?
nir: Add missing inc's to idep_nir_headers
nir.h includes:
- "compiler/glsl_types.h" -> inc_src is needed
- "util/u_atomic.h" -> "no_extern_c.h" -> inc_include needed
This makes it possible to use rust's bindgen with only nir.h
as specified include.
Signed-off-by: Christian Gmeiner <cgmeiner@igalia.com>