ac/nir: add support for nir_intrinsic_shared_atomic_fadd

Only LLVM 10+ has support.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6000>
1 file changed